Structural design is a decision-making process in which a wide spectrum of requirements, expectations, and concerns needs to be properly addressed. Engineering design criteria are considered together with societal and client preferences, and most of these design objectives are affected by the uncertainties surrounding a design. Therefore, realistic design frameworks must be able to handle multiple performance objectives and incorporate uncertainties from numerous sources into the process.
\r\n\r\nIn this study, a multi-criteria based design framework for structural design under seismic risk is explored. The emphasis is on reliability-based performance objectives and their interaction with economic objectives. The framework has analysis, evaluation, and revision stages. In the probabilistic response analysis, seismic loading uncertainties as well as modeling uncertainties are incorporated. For evaluation, two approaches are suggested: one based on preference aggregation and the other based on socio-economics. Both implementations of the general framework are illustrated\r\nwith simple but informative design examples to explore the basic features of the framework.
\r\n\r\nThe first approach uses concepts similar to those found in multi-criteria decision theory, and directly combines reliability-based objectives with others. This approach is implemented in a single-stage design procedure. In the socio-economics based approach, a two-stage design procedure is recommended in which societal preferences are treated through reliability-based engineering performance measures, but emphasis is also given to economic objectives because these are especially important to the structural designer's client. A rational net asset value formulation including losses from uncertain future earthquakes is used to assess the economic performance of a design. A recently developed assembly-based vulnerability analysis is incorporated into the loss estimation.
\r\n\r\nThe presented performance-based design framework allows investigation of various design issues and their impact on a structural design. It is a flexible one that readily allows incorporation of new methods and concepts in seismic hazard specification, structural analysis, and loss estimation.
\r\n\r\n", "doi": "10.7907/W5WE-TD86", "publication_date": "2000", "thesis_type": "phd", "thesis_year": "2000" }, { "id": "thesis:7830", "collection": "thesis", "collection_id": "7830", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06042013-091930444", "type": "thesis", "title": "Effect of Nonuniform Seismic Input on Arch Dams", "author": [ { "family_name": "Nowak", "given_name": "Paul Scott", "clpid": "Nowak-Paul-Scott" } ], "thesis_advisor": [ { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" } ], "thesis_committee": [ { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "Standard earthquake analyses of civil engineering structures use uniform ground motions even though considerable variations in both amplitude and phase can occur along the foundation interface for long-span bridges and large dams. The objective of this thesis is to quantify the effect that these nonuniformities have on the structural response.
\r\n\r\nThe nonuniform, free-field motions of the foundation interface are assumed to be caused by incident plane body waves. The medium in which these waves travel is a linear, elastic half-space containing a canyon of uniform cross section in which the structure is placed. The solutions for the free-field motions that are due to incident SH, P and SV waves are calculated using the boundary element method.
\r\n\r\nAn analysis of Pacoima (arch) dam located near Los Angeles, California, is performed for both uniform and nonuniform excitations. The important effect of nonuniformities in the free-field motions, sometimes leading to a decrease in the dam response and sometimes to an increase, is quantified.
", "doi": "10.7907/zbd0-ty45", "publication_date": "1989", "thesis_type": "phd", "thesis_year": "1989" }, { "id": "thesis:1982", "collection": "thesis", "collection_id": "1982", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05232007-074318", "type": "thesis", "title": "Experimental Investigation of the Nonlinear Seismic Response of Concrete Gravity Dams", "author": [ { "family_name": "Donlon", "given_name": "William Patrick, Jr.", "clpid": "Donlon-William-Patrick-Jr" } ], "thesis_advisor": [ { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" } ], "thesis_committee": [ { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "The nonlinear seismic response of concrete gravity dams is investigated experimentally through the use of small-scale models. Of primary interest is crack formation, crack opening and closing, and sliding along crack planes. Also of concern is the stability of the structure after cracking. Three small-scale models (length scale - 115) of a single monolith of Pine Flat Dam are tested to determine the extent of such behavior and its effect on structural stability. The models are constructed of one polymer-based and two plaster-based materials developed for these experiments. The plaster-based materials fulfill the strength, stiffness, and density requirements established by the laws of similitude, while the polymer-based material fulfills only the stiffness and density requirements and is used only in the lower part of the dam where cracking is not expected. The excitation is a modified version of the N00E component of the 1940 Imperial Valley earthquake, applied to each model's base in the stream direction through a vibration table with high-frequency capability. Tests are performed with and without water in the reservoir. The response of each earthquake test is presented in the form of acceleration and displacement time histories, Fourier spectra, and frames taken from high-speed films of the model's response. The results of the experiments indicate that the neck region of a concrete gravity dam is most susceptible to cracking, although crack profiles can differ as a result of variations in excitation, material properties, and construction techniques. These results also indicate alternate design techniques which could improve the seismic stability of a cracked gravity dam.
", "doi": "10.7907/4mqw-6z67", "publication_date": "1989", "thesis_type": "phd", "thesis_year": "1989" }, { "id": "thesis:7517", "collection": "thesis", "collection_id": "7517", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03142013-082003398", "type": "thesis", "title": "Experimental and Finite Element Studies of a Large Arch Dam", "author": [ { "family_name": "Dur\u00f3n", "given_name": "Ziyad Hassan", "clpid": "Dur\u00f3n-Ziyad-Hassan" } ], "thesis_advisor": [ { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" } ], "thesis_committee": [ { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" }, { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "Forced vibration field tests and finite element studies have been conducted on Morrow Point (arch) Dam in order to investigate dynamic dam-water interaction and water compressibility. Design of the data acquisition system incorporates several special features to retrieve both amplitude and phase of the response in a low signal to noise environment. These features contributed to the success of the experimental program which, for the first time, produced field evidence of water compressibility; this effect seems to play a significant role only in the symmetric response of Morrow Point Dam in the frequency range examined. In the accompanying analysis, frequency response curves for measured accelerations and water pressures as well as their resonating shapes are compared to predictions from the current state-of-the-art finite element model for which water compressibility is both included and neglected. Calibration of the numerical model employs the antisymmetric response data since they are only slightly affected by water compressibility, and, after calibration, good agreement to the data is obtained whether or not water compressibility is included. In the effort to reproduce the symmetric response data, on which water compressibility has a significant influence, the calibrated model shows better correlation when water compressibility is included, but the agreement is still inadequate. Similar results occur using data obtained previously by others at a low water level. A successful isolation of the fundamental water resonance from the experimental data shows significantly different features from those of the numerical water model, indicating possible inaccuracy in the assumed geometry and/or boundary conditions for the reservoir. However, the investigation does suggest possible directions in which the numerical model can be improved.
", "doi": "10.7907/e0rt-g677", "publication_date": "1988", "thesis_type": "phd", "thesis_year": "1988" }, { "id": "thesis:7516", "collection": "thesis", "collection_id": "7516", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03132013-163747278", "primary_object_url": { "basename": "Peng_cy_1988.pdf", "content": "final", "filesize": 4483872, "license": "other", "mime_type": "application/pdf", "url": "/7516/1/Peng_cy_1988.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Generalized Modal Identification of Linear and Nonlinear Dynamic Systems", "author": [ { "family_name": "Peng", "given_name": "Chia-Yen", "clpid": "Peng-Chia-Yen" } ], "thesis_advisor": [ { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" } ], "thesis_committee": [ { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "This dissertation is concerned with the problem of determining the dynamic characteristics of complicated engineering systems and structures from the measurements made during dynamic tests or natural excitations. Particular attention is given to the identification and modeling of the behavior of structural dynamic systems in the nonlinear hysteretic response regime. Once a model for the system has been identified, it is intended to use this model to assess the condition of the system and to predict the response to future excitations.
\r\n\r\nA new identification methodology based upon a generalization of the method of modal identification for multi-degree-of-freedom dynaimcal systems subjected to base motion is developed. The situation considered herein is that in which only the base input and the response of a small number of degrees-of-freedom of the system are measured. In this method, called the generalized modal identification method, the response is separated into \"modes\" which are analogous to those of a linear system. Both parametric and nonparametric models can be employed to extract the unknown nature, hysteretic or nonhysteretic, of the generalized restoring force for each mode.
\r\n\r\nIn this study, a simple four-term nonparametric model is used first to provide a nonhysteretic estimate of the nonlinear stiffness and energy dissipation behavior. To extract the hysteretic nature of nonlinear systems, a two-parameter distributed element model is then employed. This model exploits the results of the nonparametric identification as an initial estimate for the model parameters. This approach greatly improves the convergence of the subsequent optimization process.
\r\n\r\nThe capability of the new method is verified using simulated response data from a three-degree-of-freedom system. The new method is also applied to the analysis of response data obtained from the U.S.-Japan cooperative pseudo-dynamic test of a full-scale six-story steel-frame structure.
\r\n\r\nThe new system identification method described has been found to be both accurate and computationally efficient. It is believed that it will provide a useful tool for the analysis of structural response data.
", "doi": "10.7907/e70y-gz66", "publication_date": "1988", "thesis_type": "phd", "thesis_year": "1988" }, { "id": "thesis:2556", "collection": "thesis", "collection_id": "2556", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06112008-155515", "type": "thesis", "title": "Nonlinear Seismic Analysis of Arch Dams", "author": [ { "family_name": "Dowling", "given_name": "Michael John", "clpid": "Dowling-Michael-John" } ], "thesis_advisor": [ { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" } ], "thesis_committee": [ { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "A nonlinear finite element procedure for arch dams is described in which the gradual opening and closing of vertical contraction joints and predetermined horizontal cracking planes are considered. A special joint element approximately represents the deformations due to plane sections not remaining plane at each open joint and allows a single shell element discretization in the thickness direction to be used for the dam. Compressive and sliding nonlinearities are not included. Finite element treatments are also used for the water, assumed incompressible, and for the foundation rock, assumed massless, with all degrees of freedom (dof) off the dam condensed out. For efficiency in the computations, the condensed water and foundation matrices are localized in a way which maintains good accuracy. The response of Pacoima Dam to the 1971 San Fernando ground motion recorded on a ridge over one abutment and scaled by two-thirds is computed first for water at the intermediate level that existed during the 1971 earthquake and then for full reservoir. In the first analysis, the dam exhibits pronounced opening and separation of the contraction joints, allowing violation of the no-slip assumption. The presence of a full reservoir greatly increases the dam response, enough to bring some of the assumptions of the analysis into question. Reducing the ground motion scale to 0.44 with full reservoir drops the response back to a reasonable level, but the contraction joint separations remain.
\r\n\r\n", "doi": "10.7907/DJ4P-9393", "publication_date": "1988", "thesis_type": "phd", "thesis_year": "1988" }, { "id": "thesis:4460", "collection": "thesis", "collection_id": "4460", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-11082007-084824", "type": "thesis", "title": "A Numerical Evaluation of the Method of Equivalent Nonlinearization", "author": [ { "family_name": "Lin", "given_name": "Anne", "clpid": "Lin-Anne" } ], "thesis_advisor": [ { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" } ], "thesis_committee": [ { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The Method of Equivalent Nonlinearization, an approach for determining the approximate steady-state probability density function for the random response of nonlinear systems, is evaluated based on numerical simulations.
\r\n\r\nThe approach is a natural extension of the well-known Method of Equivalent Linearization, and is based on approximating the original nonlinear system by an equivalent nonlinear system. As such, the approach relies on the existence of exact solutions for the steady-state probability density function of nonlinear systems.
\r\n\r\nThe approach is applied to a class of systems with nonlinear damping, for which there are no exact solutions. The results show an excellent agreement between simulated and predicted probability density functions for displacement, velocity and energy-based envelope. Several examples were solved, including the case of (velocity)m-damping and the Van der Pol equation.
\r\n", "doi": "10.7907/31g4-p045", "publication_date": "1988", "thesis_type": "phd", "thesis_year": "1988" }, { "id": "thesis:11411", "collection": "thesis", "collection_id": "11411", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02272019-105053083", "primary_object_url": { "basename": "Jayakumar_P_1987.pdf", "content": "final", "filesize": 60979801, "license": "other", "mime_type": "application/pdf", "url": "/11411/1/Jayakumar_P_1987.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Modeling and Identification in Structural Dynamics", "author": [ { "family_name": "Jayakumar", "given_name": "Paramsothy", "clpid": "Jayakumar-Paramsothy" } ], "thesis_advisor": [ { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" } ], "thesis_committee": [ { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "Analytical modeling of structures subjected to ground motions is an important aspect of fully dynamic earthquake-resistant design. In general, linear models are only sufficient to represent structural responses resulting from earthquake motions of small amplitudes. However, the response of structures during strong ground motions is highly nonlinear and hysteretic.
\r\n\r\nSystem identification 1s an effective tool for developing analytical models from experimental data. Testing of full-scale prototype structures remains the most realistic and reliable source of inelastic seismic response data. Pseudo-dynamic testing is a recently developed quasi-static procedure for subjecting full-scale structures to simulated earthquake response. The present study deals with structural modeling and the determination of optimal linear and nonlinear models by applying system identification techniques to elastic and inelastic pseudo-dynamic data from a full-scale, six-story steel structure.
\r\n\r\nIt is shown that the feedback of experimental errors during the pseudo-dynamic tests significantly affected the higher modes and led to an effective negative damping for the third mode. The contributions of these errors are accounted for and the small-amplitude modal properties of the test structure are determined. These properties are in agreement with the values obtained from a shaking table test of a 0.3 scale model.
\r\n\r\nThe nonlinear hysteretic behavior of the structure during strong ground motions is represented by a general class of Masing models. A simple model belonging to this class is chosen. with parameters which can be estimated theoretically, thereby making this type of model potentially useful during the design stages. The above model is identified from the experimental data and then its prediction capability and application in seismic design and analysis are examined.
", "doi": "10.7907/1wwx-ca82", "publication_date": "1987", "thesis_type": "phd", "thesis_year": "1987" }, { "id": "thesis:6712", "collection": "thesis", "collection_id": "6712", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10132011-090721112", "primary_object_url": { "basename": "Vidale_je_1987.pdf", "content": "final", "filesize": 24558213, "license": "other", "mime_type": "application/pdf", "url": "/6712/1/Vidale_je_1987.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Application of Two-Dimensional Finite-Difference Wave Simulation to Earthquakes, Earth Structure, and Seismic Hazard", "author": [ { "family_name": "Vidale", "given_name": "John Emilio", "clpid": "Vidale-John-Emilio" } ], "thesis_advisor": [ { "family_name": "Hager", "given_name": "Bradford H.", "clpid": "Hager-B-H" }, { "family_name": "Clayton", "given_name": "Robert W.", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Ahrens", "given_name": "Thomas J.", "clpid": "Ahrens-T-J" } ], "thesis_committee": [ { "family_name": "Ahrens", "given_name": "Thomas J.", "clpid": "Ahrens-T-J" }, { "family_name": "Helmberger", "given_name": "Donald V.", "clpid": "Helmberger-D-V" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Clayton", "given_name": "Robert W.", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Hager", "given_name": "Bradford H.", "clpid": "Hager-B-H" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "Although the earth is 3-dimensional (3-D), numerical simulations of wave propagation through laterally heterogeneous media are easier to formulate and more practical to use in 2-D. In this thesis, schemes to model seismic wave propagation through laterally varying structures with 2-D numerical algorithms are developed and applied to earthquake and explosion problems.
\r\n\r\nIn Chapter 1, 2-D source expressions that have the same radiation patterns as their 3-D counterparts are derived which can rectify the following three problems: the use of 2-D simulations generally results in \"line source tails\" on what would be impulsive arrivals in 3-D, 1/\u221aR rather than 1/R amplitude decay for body waves, and no decay rather than 1/\u221aR amplitude decay for surface waves. Because this technique approximately transforms waves from a cartesian 2-D grid to a cylindrically symmetric 3-D world, slightly anisotropic geometrical spreading in 2-D better approximates isotropic spreading in 3-D than simple isotropic spreading in 2-D does. In Section 1.7, a correction to the explosive source expression reduces energy traveling vertically out of the source region, but leaves unchanged the energy traveling laterally out of the source region. In some cases, this correction will significantly improve the results of using a 2-D grid to simulate elastic wave propagation from an explosive point source.
\r\n\r\nIn Chapter 2, synthetic seismograms are constructed for the strong motions of the 1968 Borrego Mountain earthquake recorded at EI Centro. A good fit to the data results from using the laterally varying model determined by a detailed refraction survey and the source parameters determined by teleseismic waveform modeling. Shallow faulting is no longer necessary to explain the long-period surface-wave development.
\r\n\r\nSynthetic seismograms calculated for the 1971 San Fernando earthquake show strong effects due to lateral variation in sediment thickness in the San Fernando valley and the Los Angeles basin. Using previously determined basin structure and teleseismically determined source parameters, two-dimensional SH and P-SV finite difference calculations can reproduce the amplitude and duration of the strong motion velocities recorded across the basins in Los Angeles in the period range from 1 to 10 seconds. The edges of basins nearest the seismic source show ground motion amplification up to a factor of three, and tend to convert direct shear waves into Love and Rayleigh waves that travel within the basins. The computed motions are sensitive to the mechanism and location of earthquakes. A strike-slip earthquake on the Newport-Inglewood fault zone, for example, would produce different patterns of peak velocity and duration of shaking across the San Fernando and Los Angeles basins.
\r\n\r\nIn Chapter 3, the effect of shallow station structure and lateral velocity variation are investigated for records of the Amchitka explosion Milrow. The differences between the Meuller-Murphy, Heimberger-Hadley, and von Seggern-Blandford reduced displacement potential (RDP) source representations are small compared to the differences between using various possible velocity structures.
\r\n\r\nCreager and Jordan (1986) propose that penetration of subducting slabs under the Kurile Islands and other subduction zones to depths of at least 1000 km is necessary to explain the t ravel time anomalies of deep earthquakes. Such penetration would also affect the amplitudes and waveforms of the body waves from these earthquakes. In Chapter 4, synthetic seismograms appropriate for a record section in a plane perpendicular to the strike of the slab are presented using a coupled finite-difference and Kirchhoff method. An inferred shear-wave version of the compressional-wave velocity structure of Creager and Jordan (1986) produces an amplitude decrease up to a factor of four and waveform broadening up to 20 seconds for SH arrivals with a take-off angle pointing straight down t he slab. Slabs that extend only 300 km below the earthquake but are half as thick and twice as anomalously fast as Creager and Jordan 's (1986) velocity model will roughly preserve the travel time variation pattern, and show less waveform broadening, but produce first arrivals that are emergent. Slabs that become thicker with depth show less waveform broadening. Reconciliation of the amplitude, waveform distort ion, and timing of body waves from deep events is necessary to understand the geometry of slabs near and below the 6.50 km discontinuity.
", "doi": "10.7907/7TQ9-X746", "publication_date": "1987", "thesis_type": "phd", "thesis_year": "1987" }, { "id": "thesis:825", "collection": "thesis", "collection_id": "825", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-03012008-132659", "primary_object_url": { "basename": "Burridge_pb_1987.pdf", "content": "final", "filesize": 27718318, "license": "other", "mime_type": "application/pdf", "url": "/825/1/Burridge_pb_1987.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Failure of Slopes", "author": [ { "family_name": "Burridge", "given_name": "Paul Brian", "clpid": "Burridge-Paul-Brian" } ], "thesis_advisor": [ { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "thesis_committee": [ { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Sieh", "given_name": "Kerry E.", "clpid": "Sieh-K-E" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The dynamic mechanism of slope failure is studied both experimentally and analytically to establish the spatial and temporal process of failure initiation and propagation during collapse of a natural or man-made slope.
\r\n\r\nModel slopes, constructed of a brittle cemented sand material, are tested to collapse in a geotechnical centrifuge and the dynamics of failure recorded by motion picture film and mechanical detectors within the slope specimen. Shear failure is observed to initiate at the toe and propagate rapidly to the crest in the presence of crest tension cracking.
\r\n\r\nA finite difference approach is taken to numerically solve the plane strain slope stability problem under gravity, based on unstable material behavior. Using a Lagrangian differencing scheme in space and explicit integration in time with dynamic relaxation, the numerical method finds the equilibrium state of the slope as the large-time limit of a dynamic problem with artificial parameters. The solution predicts localized shear failure zones which initiate at the slope toe and propagate to the slope crest in the manner and geometry observed in the centrifuge tests. In so doing, the finite difference algorithm also demonstrates an apparent ability to predict shear failure mechanisms in solid continua in general.
\r\n", "doi": "10.7907/2C4G-6R71", "publication_date": "1987", "thesis_type": "phd", "thesis_year": "1987" }, { "id": "thesis:2590", "collection": "thesis", "collection_id": "2590", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06142006-131434", "primary_object_url": { "basename": "Prairie_mr_1987.pdf", "content": "final", "filesize": 7051592, "license": "other", "mime_type": "application/pdf", "url": "/2590/1/Prairie_mr_1987.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Steady-State and Transient Methods for Modeling Chemical Reactions on Supported Catalysts", "author": [ { "family_name": "Prairie", "given_name": "Michael Roland", "clpid": "Prairie-Michael-Roland" } ], "thesis_advisor": [ { "family_name": "Bailey", "given_name": "James E.", "clpid": "Bailey-J-E" } ], "thesis_committee": [ { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Sabersky", "given_name": "Rolf H.", "clpid": "Sabersky-R-H" }, { "family_name": "Bailey", "given_name": "James E.", "clpid": "Bailey-J-E" } ], "local_group": [ { "literal": "div_chem" } ], "abstract": "A systematic experimental strategy based on fluid-phase measurements is proposed for modeling dynamic behavior of heterogeneous catalytic reactions. The strategy utilizes steady-state rate, step-response, cycled-feedstream, and feedback-induced bifurcation techniques. Ethylene hydrogenation on Pt/Al2O3 was studied using this strategy. In addition, transmission infrared spectroscopy is applied to investigate support effects which accompany ethylene hydrogenation on Pt/Al2O3, and to the detailed study of CO adsorption, desorption and oxidation on Rh/Al2O3. The proposed experimental strategy combined with surface infrared spectroscopy provides a very powerful means for identification and validation of dynamic kinetic models.
\r\n\r\nObserved bifurcation behavior can be accurately attributed to a model for the catalytic reaction only if each dynamic element in the closed-loop experimental hardware is properly accounted for. Accordingly, time delay and feedback gain were the manipulated parameters in a feedback-induced bifurcation scheme aimed at validating a dynamic model for an experimental gas-phase reactor flow system without reaction. The apparatus consists of an isothermal, stirred, fixed-bed reactor, mass flow controllers, an infrared gas analysis system, and a computerized data acquisition and control system. Experimental bifurcations to sustained oscillations show that the stability of the reactor system is strongly influenced by delay. The relationships of time delay to Hopf bifurcation gains and frequencies provide a very sensitive basis for model comparisons.
\r\n\r\nSteady-state, step-response, feedback-induced Hopf bifurcation and forced concentration cycling experiments were applied to study ethylene hydrogenation over 0.05% Pt/Al2O3 at 80\u00b0C. Step-response experiments indicate a time scale of 5000 s which is associated with chemisorbed hydrogen. Conversely, feedback-induced Hopf bifurcation data indicate this time scale to be on the order of 1 s in magnitude. In the overall strategy of dynamic modeling, the two techniques are complementary since each inherently focuses on an opposite region in the spectrum of time scales for the reactor system. Cycling the feedstream composition resulted in improvement of the time-average reaction rate for the ethylene hydrogenation reaction compared to steady-state reactor operation.
\r\n\r\nSteady-state, step-response and Hopf bifurcation data are also presented for 0.5% Pt/Al2O3 at 30\u00b0C and compared with results for the 0.05% Pt/Al2O3 catalyst. A single value of 2.5 s for the surface time constant associated with chemisorbed hydrogen is sufficient for modeling behavior on 0.5% Pt/Al2O3, whereas the lower-loaded 0.05% Pt/Al2O3 catalyst requires two very different values. In addition, the 0.5% catalyst was used to demonstrate the general result that small discrepancies between the actual and chosen reference steady state give rise to imperfect, cusp-like bifurcations. Steady-state bifurcation data are also shown to be useful for discriminating among rival kinetic models.
\r\n\r\nEthylene hydrogenation on spillover-activated alumina is proposed as an explanation for the very slow transient behavior observed for 0.05% Pt/Al2O3. Transmission infrared spectroscopy was used to study hydrogen spillover dynamics on 0.05% Pt/Al2O3 at 80\u00b0C via hydroxyl/deuteroxyl exchange. Ethylene in the gas-phase markedly slows the rate of spillover. The presence of ethylene likely reduces the concentration of platinum-adsorbed hydrogen adatoms, the precursors of hydrogen spilled onto alumina, due to catalytic hydrogenation on the platinum. Surface transport of hydrogen atoms on spillover-activated alumina is proposed as an explanation for the very slow transient behavior observed for ethylene hydrogenation on 0.05% Pt/Al2O3. Infrared spectra exhibit characteristics of both hydroxyl and deuteroxyl groups for reactor feed containing only D2 and C2H4. This observation confirms the existence of a dissociative ethylene adsorption process.
\r\n\r\nA section of the thesis unrelated to ethylene hydrogenation investigates modeling applications of transmission infrared spectoscopy (TIR) by applying it to study adsorbed CO on Rh/Al2O3 during CO chemisorption, steady-state, step-response, and forced-cycling oxidation experiments at 900 torr. At 300\u00b0C, the catalyst initially supported primarily a dicarbonyl CO species, but after use exhibited spectra characteristic of a surface mostly covered by linearly bound CO. A model that describes transient, diffusion-influenced CO adsorption and desorption for the supported catalyst is presented. It suggests that the CO desorption energy depends linearly on coverage, and that the magnitude of this dependence is a function of temperature. Observed rate dependence on bulk CO concentration for O2 effluent levels of 0.5% and 0.25% is interpreted considering the effects of internal and external mass transport at 300\u00b0C. Step-response and forced-cycling oxidation experiments across stoichiometric conditions exhibit oxygen and CO storage effects characteristic of CO oxidation catalysts. Data indicating autonomous oscillation of CO coverage and CO2 production are also presented.
", "doi": "10.7907/x3zp-aa54", "publication_date": "1987", "thesis_type": "phd", "thesis_year": "1987" }, { "id": "thesis:3506", "collection": "thesis", "collection_id": "3506", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09122007-111121", "primary_object_url": { "basename": "Synolakis_ce_1986.pdf", "content": "final", "filesize": 11972309, "license": "other", "mime_type": "application/pdf", "url": "/3506/1/Synolakis_ce_1986.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Runup of Long Waves", "author": [ { "family_name": "Synolakis", "given_name": "Constantine Emmanuel", "orcid": "0000-0003-0140-5379", "clpid": "Synolakis-Constantine-Emmanuel" } ], "thesis_advisor": [ { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" } ], "thesis_committee": [ { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" }, { "family_name": "List", "given_name": "E. John", "clpid": "List-E-J" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Whitham", "given_name": "Gerald Beresford", "clpid": "Whitham-G-B" }, { "family_name": "Imberger", "given_name": "Jorg", "clpid": "Imberger-J" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This is a study of the fundamental physical processes of the runup of long waves with the objective to understand some coastal effects of tsunamis.
\r\n\r\nThe runup of nonbreaking long waves on plane beaches is studied and an exact solution is developed for the runup of solitary waves. The maximum runup predicted by this solution is compared to laboratory data from this and other investigations and it is found to be in good agreement. A runup transducer was developed and deployed in the laboratory to provide data for the shape of the runup tongue. The exact solution is shown to model the details of the climb of the wave satisfactorily.
\r\n\r\nThe runup of breaking long waves on plane beaches is investigated in the laboratory by studying different long waves and bores of finite volume. The runup is shown to be a function of a momentum scale determined from the generation characteristics of the incoming wave. The runup number is introduced and it is demonstrated that it models the runup process adequately. It is also observed that arbitrary long waves have runup numbers smaller than, or at most equal to, the runup number of breaking solitary waves, suggesting that on a given plane beach breaking solitary waves run-up further than other long waves with similar generation characteristics.
\r\n\r\nAn exact result is established for the force on an accelerating plate in a fluid with a free surface. The result is used to explain some of the results of this study and other results on the hydrodynamic forces on moving partitions.
\r\n\r\nA technique is developed to generate arbitrary, long, continuously evolving waves at any desired location in a laboratory model. The technique is applied in the laboratory and it is shown to be successful in reproducing complex waveforms.
", "doi": "10.7907/REBC-D787", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:11848", "collection": "thesis", "collection_id": "11848", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10232019-110854163", "type": "thesis", "title": "Analysis of Unanchored Liquid Storage Tanks under Seismic Loads", "author": [ { "family_name": "Peek", "given_name": "Ralf", "orcid": "0000-0002-2469-3644", "clpid": "Peek-Ralf" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" }, { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "Because of cost, cylindrical, ground supported liquid storage tanks are often not fixed to their foundation, even in seismic areas. For such an unanchored tank made of steel, the weight of the cylindrical shell is mostly insufficient to prevent local uplift due to seismic overturning moments. Although, for properly designed connecting pipes, uplift itself is not a problem, it results in larger vertical compressive stresses in the tank wall at the base, opposite to where the uplift occurs. These compressive stresses have often caused buckling, even in earthquakes which did not cause much damage to other structures.
\r\n\r\nVarious investigators have studied the behavior of unanchored tanks experimentally, but, due to the complexity of the problem, so far very little theoretical work has been done. Two methods of analysis for static lateral loads are presented: An approximate one in which the restraining action of the base plate is modeled by nonlinear Winkler springs, and a more comprehensive one in which the two dimensional nonlinear contact problem is solved by the finite difference energy method. The theoretical results are compared with existing experimental results and with the approach from current U.S. design standards. The theoretical peak compressive stresses are in good agreement with the experimental results, but in some cases exceed those calculated by the code method by more than 100%.
\r\n\r\nFinally, a new design concept, by which the tank wall is preuplifted all around its circumference by inserting a ring filler is described. It will be shown theoretically and experimentally that this preuplift method substantially improves the lateral load capacity.
", "doi": "10.7907/w43k-hj54", "publication_date": "1986", "thesis_type": "phd", "thesis_year": "1986" }, { "id": "thesis:11355", "collection": "thesis", "collection_id": "11355", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01222019-152401456", "primary_object_url": { "basename": "Pak_RYS_1985.pdf", "content": "final", "filesize": 25113861, "license": "other", "mime_type": "application/pdf", "url": "/11355/1/Pak_RYS_1985.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Dynamic Response of a Partially Embedded Bar Under Transverse Excitations", "author": [ { "family_name": "Pak", "given_name": "Ronald Y.S.", "clpid": "Pak-Ronald-Y-S" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Sternberg", "given_name": "Eli", "clpid": "Sternberg-E" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" }, { "family_name": "Wu", "given_name": "Theodore Yao-tsu", "clpid": "Wu-T-Y-T" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "This dissertation is concerned with the dynamic response of a finite flexible bar partially embedded in a half-space, under transverse loadings. The loadings are applied at the unembedded end of the bar and may, in general, be a combination of time-harmonic shear and moment. The problem is intended to serve as a fundamental idealization for the dynamic analysis of piles or other embedded foundations whose flexibilities are not negligible.
\r\n\r\nBy treating the bar as a one-dimensional structure and the half-space as a three-dimensional elastic continuum, the interaction problem is formulated as a Fredholm integral equation of the second kind. The essential tool required in the formulation is a group of Green's functions which describe the response of an elastic half-space to a finite, distributed, buried source which acts in the lateral direction. By means of a technique developed for a class of three-dimensional asymmetric wave propagation problems, the Green's functions are derived as integral representations. A numerical procedure for the computation of the semi-infinite Hankel-type integrals involved is presented which is free of the basic difficulties commonly encountered in such problems. Owing to the special nature of the kernel function, a numerical scheme which contains the essence of quadrature and collocation techniques is developed for the solution of the governing integral equation. Selected results for the interaction problem are presented to illustrate various basic features of the solution. In addition to furnishing the compliance functions commonly used in soil-structure interaction studies, the solution should prove useful in providing a basis for the assessment and improvement of approximate and numerical models currently employed for such analyses.
", "doi": "10.7907/pp2r-fc10", "publication_date": "1985", "thesis_type": "phd", "thesis_year": "1985" }, { "id": "thesis:11322", "collection": "thesis", "collection_id": "11322", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:12192018-105342164", "primary_object_url": { "basename": "Cifuentes_AO_1985.pdf", "content": "final", "filesize": 38763233, "license": "other", "mime_type": "application/pdf", "url": "/11322/1/Cifuentes_AO_1985.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "System Identification of Hysteretic Structures", "author": [ { "family_name": "Cifuentes", "given_name": "Arturo O.", "orcid": "0000-0001-9689-3939", "clpid": "Cifuentes-Arturo-O" } ], "thesis_advisor": [ { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "This thesis is concerned with the earthquake response of hysteretic structures subjected to strong ground acceleration. Several earthquake records corresponding to different instrumented buildings are analyzed. Based on these observations, a new model for the dynamic behavior of reinforced concrete buildings is proposed. In addition, a suitable system identification algorithm to be used with this new model is introduced. This system identification algorithm is based upon matching the restoring force behavior of the structure rather than the time history of the response. As a consequence, the new algorithm exhibits significant advantages from a computational point of view. Same numerical examples using actual earthquake data are discussed.
", "doi": "10.7907/p43n-j428", "publication_date": "1985", "thesis_type": "phd", "thesis_year": "1985" }, { "id": "thesis:11391", "collection": "thesis", "collection_id": "11391", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02132019-102055741", "primary_object_url": { "basename": "Maragakis_E_1985.pdf", "content": "final", "filesize": 56196907, "license": "other", "mime_type": "application/pdf", "url": "/11391/1/Maragakis_E_1985.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "A Model for the Rigid Body Motions of Skew Bridges", "author": [ { "family_name": "Maragakis", "given_name": "Emmanuel", "clpid": "Maragakis-Emmanuel" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Hall", "given_name": "John F.", "clpid": "Hall-J-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Wu", "given_name": "Theodore Yao-tsu", "clpid": "Wu-T-Y-T" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "This thesis investigates the rigid body motions of skew bridges, concentrating on the in-plane translational and rotational displacements of the bridge deck induced by impact between the deck and the abutments. Experience in the San Fernando Earthquake of February 9, 1971 demonstrates that this feature is particularly important for skew bridges.
\r\n\r\nA simple model, in which the bridge deck is represented by a rigid rod restricted by column and abutment springs is examined first. This model illustrates the mechanism by which in-plane rotational vibrations is triggered after the closure of the gap between the bridge deck and the abutment. It also shows that the force-deflection relations of the columns and the abutments are particularly important features for the response of the bridge. Methods for the exact and approximate estimation of the elastic stiffness of elastically founded, tapered bridge columns with octagonal cross section are presented next. The methods are applied to a bridge used later as an example. In addition, the yielding of the columns is examined and the force-deflection relations for bending about two orthogonal axes are estimated.
\r\n\r\nThe abutments are treated as rigid bodies and the soil embankments as Winkler Foundations with elastic spring constants increasing with depth. For the examination of the yielding of soil the Rankine theory is used. Based on these assumptions an approximate force deflection relation for the abutments is constructed.
\r\n\r\nThe response of a more complicated bridge model applied to a bridge near Riverside, California is examined at the end of the thesis and examples of the results are given. This model, in which the bridge deck is still represented as a rigid rod, has three in-plane degrees of freedom: two orthogonal displacements and a rotation, and is capable of capturing many of the more important features of the nonlinear, yielding response of skew bridges during strong earthquake shaking.
", "doi": "10.7907/YWES-NJ36", "publication_date": "1985", "thesis_type": "phd", "thesis_year": "1985" }, { "id": "thesis:11308", "collection": "thesis", "collection_id": "11308", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:12122018-092221333", "primary_object_url": { "basename": "Huang_M_1984.pdf", "content": "final", "filesize": 79571343, "license": "other", "mime_type": "application/pdf", "url": "/11308/1/Huang_M_1984.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Investigation of Local Geology Effects on Strong Earthquake Ground Motions", "author": [ { "family_name": "Huang", "given_name": "Moh-jiann", "clpid": "Huang-Moh-jiann" } ], "thesis_advisor": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" } ], "thesis_committee": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Knauss", "given_name": "Wolfgang Gustav", "clpid": "Knauss-W-G" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "Accelerograms recorded at four stations in the Pasadena area during the 1971 San Fernando, the 1970 Lytle Creek, the 1968 Borrego Mountain and the 1952 Kern County earthquakes are analyzed to investigate local geology effects on strong earthquake ground motions. Spatial variations of the ground motions at two nearby stations are also investigated. It is found that the ground motions in this area caused by the local geology effects depend on the 3- dimensional configuration of the local geology and the direction of arriving seismic waves. Local geology effects are less evident on the leading portions of the accelerograms than the trailing portions, indicating the effects of local geology on surface wave propagations. Comparison of the Fourier amplitudes of the motions recorded at the same station during different earthquakes shows that there are no significant spectral peaks can be identified as site periods. Hence, it is not appropriate to characterize such local sites by a site period.
\r\n\r\nA two-dimensional model considering inclined propagating P and S waves in a horizontal-layered structure, which is more realistic and closer to the actual seismic environment within a local geology than the one-dimensional model of vertically propagating waves, is studied. The transfer functions between the free surface and the half-space outcrop for a single incident P, SV or SH wave from the half-space at an incident angle are defined and derived by a matrix method. Two numerical examples are given to demonstrate the effects of incident angle and material damping on the transfer function. It is found that the transfer function between the free surf ace motions and the bedrock outcrop motions to multiple incident waves having different amplitudes, angles and arrival times is quite different from that for a single incident wave. Completely satisfactory results cannot be expected when using the analytical model for evaluating the local geology effects on the motions during a nearby shallow-focus earthquake for which seismic waves emitted from different parts of the fault will approach the bedrock from different directions and at different angles.
\r\n\r\nThe analytical model for assessing local geology effects is evaluated in the light of the data recorded at stations in the Pasadena area during the 1971 San Fernando earthquake. The observed site transfer functions between the alluvial and the rock sites are obtained and compared with the computed results from a two-dimensional model with 7-layers overlying a half-space. Values of model parameters are optimally adjusted to give a best least-squares fit between computed and observed amplitude ratios. It is concluded that the analytical model oversimplifies the local geological structure in the Pasadena area and the actual seismic environment in the area during the 1971 San Fernando earthquake.
\r\n\r\nIt is concluded from these studies that the effects of the source mechanism and the seismic wave travel paths upon the site ground motion can be comparable to the effect of the local geology. The characteristics of the source mechanism, such as type of faulting, direction of fault-slip propagation, nature of stress drop across the fault surface, orientation of fault, depth beneath ground surface, etc., can appreciably influence the ground motion at the site. Also, the travel path can have a significant effect through influencing the types of waves that reach the site, and the directions of approach of the waves. The results of this study indicate that a better understanding of the spatial variation of ground motions, of the role played by different types of waves and their contributions to an accelerogram, and of the propagation directions of the waves is needed for assessing local geology effects on earthquake ground motions. A local array is desirable to provide data for giving a reasonably complete picture of the nature of ground motions in a local area.
", "doi": "10.7907/pm3k-w086", "publication_date": "1984", "thesis_type": "phd", "thesis_year": "1984" }, { "id": "thesis:11283", "collection": "thesis", "collection_id": "11283", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11262018-124513833", "type": "thesis", "title": "Analysis of the Observed Earthquake Response of a Multiple Span Bridge", "author": [ { "family_name": "Wilson", "given_name": "John Charles", "clpid": "Wilson-John-Charles" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Hall", "given_name": "John F.", "orcid": "0000-0002-7863-5060", "clpid": "Hall-J-F" }, { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" }, { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Accelerograms obtained during the 1979 Coyote Lake, California earthquake are used to examine the response of a multiple-span, steel girder bridge to strong earthquake loading. The structure studied, the San Juan Bautista 156/101 Separation Bridge, is typical of many highway bridges in seismic regions of the United States. Although the bridge was not damaged, the strong-motion records are of significant engineering interest as they are the first to be recorded on such a structure.
\r\n\r\nAn engineering seismology study suggests that long-period ground displacements at the bridge site were caused by Rayleigh waves. A three-second period, pseudostatic response of the superstructure is attributed to small amounts of differential support motion induced by the surface waves.
\r\n\r\nA time-domain technique of system identification is used to determine linear models which can closely replicate the observed bridge response. Using time-invariant models, two structural modes at 3.50 and 6.33 Hz, are identified in the horizontal direction. Each mode, having approximately ten-percent damping, involves coupled longitudinal and transverse motions of the superstructure. Time-variations of frequency and damping in the horizontal response are also identified using a moving-window analysis.
\r\n\r\nA three-dimensional finite element model which includes soil-structure interaction predicts several important features of the dynamic response of the bridge. The first two computed horizontal frequencies are found to be in excellent agreement with the observed responses provided the model's expansion joints are locked, preventing relative translational motions from occurring across the joints. Locking is confirmed by the observed deformations of the structure in the fundamental mode. Fundamental vertical frequencies of the individual spans, predicted by the finite element model, are in very good agreement with ambient vibration test data. Results of the strong-motion data analysis and the finite element modeling are used to recommend a plan for expansion of the strong-motion instrumentation array on the bridge.
", "doi": "10.7907/5321-6p57", "publication_date": "1984", "thesis_type": "phd", "thesis_year": "1984" }, { "id": "thesis:3060", "collection": "thesis", "collection_id": "3060", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08092005-091223", "type": "thesis", "title": "Analysis and Control of Quasi Distributed Parameter Systems", "author": [ { "family_name": "Goh", "given_name": "Chuen Jin", "clpid": "Goh-Chuen-Jin" } ], "thesis_advisor": [ { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" } ], "thesis_committee": [ { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Wood", "given_name": "Lincoln", "clpid": "Wood-L" }, { "family_name": "Thompson", "given_name": "Peter M.", "clpid": "Thompson-Peter-M" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "As engineering systems become larger and more flexible, serious consideration must be given to the very high order, and consequently very high bandwidth, of these so called quasi-distributed parameter systems. In particular, as practical active control devices such as sensors and actuators have finite bandwidth, great care must be exercised so that control of low frequency modes does not cause instability of intermediate and high frequency modes. In this report, the nature of these stability problems is investigated in the context of direct velocity feedback control, and approximate bounds on the diagonal elements of the modal gain matrix are derived. Two velocity feedback techniques are proposed to alleviate potential instability, but these are dependent on the natural damping of the system, which remains uncertain in practice. Another technique using position feedback is considered. Despite certain additional complications, position feedback control proves to be more advantageous in many ways than velocity feedback. Some preliminary analyses on a quasi-linear vibration suppression technique via damping matrix modification are also presented. The feasibility of these theoretical techniques are confirmed by means of a numerical simulation on a simply supported discrete shear beam.
\r\n", "doi": "10.7907/96PH-6521", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:11363", "collection": "thesis", "collection_id": "11363", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01252019-143659174", "primary_object_url": { "basename": "Rashed_A_1983.pdf", "content": "final", "filesize": 44432116, "license": "other", "mime_type": "application/pdf", "url": "/11363/1/Rashed_A_1983.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Dynamic Analyses of Fluid-Structure Systems", "author": [ { "family_name": "Rashed", "given_name": "Ahmed Atef", "clpid": "Rashed-Ahmed-Atef" } ], "thesis_advisor": [ { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" } ], "thesis_committee": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" }, { "family_name": "Franklin", "given_name": "Joel N.", "clpid": "Franklin-J-N" }, { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Theoretical investigations of the dynamic behavior of some important fluid-structure systems are conducted to seek a better understanding of: 1) the hydrodynamic pressures generated in the fluid as a result of both the rigid body and the vibrational motions of the structure, and 2) the effects of the fluid on the dynamic properties of the structure as well as on its response to earthquake ground motions.
\r\n\r\nExplicit formulas are presented for the hydrodynamic pressures generated in fluid domains having boundaries which can be approximated by simple geometries. Such domains may be reservoirs behind dams, or around intake towers, water around bridge piers or liquids stored in circular cylindrical tanks. The formulas are used to calculate the hydrodynamic pressures analytically and the results are exhibited in a form showing the pressure dependence on the various parameters of the problem.
\r\n\r\nThe fluid-structure interaction problems of long straight walls, having uniform rectangular sections, and long straight gravity dams, having uniform triangular sections, are investigated. The natural frequencies of vibration and the associated mode shapes are found in the former case, through a fully analytical approach for both the structure and the fluid domains, and in the latter, by discretizing the dam into finite elements and treating the reservoir as a continuum by boundary solution techniques. A method is presented for computing the earthquake response of both structures, based on superposition of their free vibrational modes.
\r\n\r\nThe problems of limited length dam or wall-reservoir systems are investigated. The natural frequencies of the structure and the corresponding mode shapes are found by the Rayleigh-Ritz method. This method is also used to obtain the frequency domain response of the structure to all three components of the ground motion. The validity of the two dimensional approximation, often made in the analysis of gravity dams, and the effect of the length to height ratio on the dynamic properties and response of the structure are studied.
\r\n\r\nTime domain responses to arbitrary earthquake ground motions are evaluated by superposing the frequency domain responses, to individual Fourier components of the excitation, through the Fourier Integral. For efficiency of computation, a fast Fourier analysis is used for both the forward transform of the ground excitation and the inverse transform of the Fourier Integral.
", "doi": "10.7907/1yc0-fm70", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:11761", "collection": "thesis", "collection_id": "11761", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08162019-113014700", "primary_object_url": { "basename": "Jain_SK_1983.pdf", "content": "final", "filesize": 45748031, "license": "other", "mime_type": "application/pdf", "url": "/11761/1/Jain_SK_1983.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Analytical Models for the Dynamics of Buildings", "author": [ { "family_name": "Jain", "given_name": "Sudhir Kumar", "clpid": "Jain-Sudhir-Kumar" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" }, { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "Caltech Distinguished Alumni Award" }, { "literal": "div_eng" } ], "abstract": "This thesis investigates the significance of in-plane floor flexibility on the dynamics of buildings, and develops analytical models for structures that have flexible floor diaphragms. Experience with past earthquakes demonstrates that this feature is particularly important for long, narrow buildings and buildings with stiff end walls. In the method developed in this study, the equations of motion and appropriate boundary conditions for various elements of the structure are written in a single coordinate system and then are solved exactly.
\r\n\r\nOne- and two-story buildings with end walls are analyzed by treating their floors and walls as bending and shear beams, respectively. The resulting equations of motion and the boundary conditions are solved to obtain the dynamic properties of the structure. The expected low torsional stiffness of the end walls or frames is confirmed by analysis of a single-story example structure. Study of a similar two-story building showed that the first two modes, dominated by the floor and the roof vibrations, make the largest contributions to the total base shear in the structure.
\r\n\r\nFloors of multistory buildings with end walls (or frames) are idealized as equivalent, distributed beams while the walls or frames are treated as bending or shear beams. Analysis of a nine-story building showed that the structure possesses several lower modes in which floors vibrate essentially as pinned-pinned beams.
\r\n\r\nBuildings with large numbers of uniform stories and frames (or walls) are treated as vertically-oriented anisotropic plates. It is concluded that the floors in such buildings can be assumed rigid for seismic analysis, since the modes involving floor deformations are not excited by uniform ground motion.
\r\n\r\nThe approach can be generalized further to study more complex structures. An example is the Imperial County Services Building, which has two end walls in the upper stories and several walls in the ground story. The analytical model of this building predicts several important features of the complex dynamic behavior of the structure.
\r\n", "doi": "10.7907/4k04-ca84", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:3374", "collection": "thesis", "collection_id": "3374", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09072006-111327", "primary_object_url": { "basename": "Liu_hl_1983.pdf", "content": "final", "filesize": 8891780, "license": "other", "mime_type": "application/pdf", "url": "/3374/1/Liu_hl_1983.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Interpretation of Near-Source Ground Motion and Implications", "author": [ { "family_name": "Liu", "given_name": "Hsui-Lin", "clpid": "Liu-Hsui-Lin" } ], "thesis_advisor": [ { "family_name": "Harkrider", "given_name": "David G.", "clpid": "Harkrider-D-G" } ], "thesis_committee": [ { "family_name": "Helmberger", "given_name": "Donald V.", "clpid": "Helmberger-D-V" }, { "family_name": "Clayton", "given_name": "Robert W.", "orcid": "0000-0003-3323-3508", "clpid": "Clayton-R-W" }, { "family_name": "Harkrider", "given_name": "David G.", "clpid": "Harkrider-D-G" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" } ], "local_group": [ { "literal": "div_gps" } ], "abstract": "This thesis presents some deterministic modeling and interpretation of various aspects of observed near-source ground motions.
\r\n\r\nIn Chapter 1, finite source parameters determined from waveform modeling studies are presented for two California earthquakes; the 1979 Coyote Lake event and the 1966 Parkfield event. These events were recorded by strong motion arrays with similar station to fault rupture geometries. Thus it is possible to demonstrate that differences in the ground motions recorded within 30 km of the epicenter are indeed due to the differences in rupture fault length and dislocation distribution.
\r\n\r\nDetails of the waveform modeling for the August 6, 1979 Coyote Lake earthquake are described in part 1-A. A finite fault striking N24\u00b0W and extending to a depth of 10 km is proposed to model the strong-ground motion data. The source model suggests that right-lateral faulting initiated at a depth of 8 km and ruptured towards the south with a velocity of 2.8 km/sec. This unilateral rupture can explain the large displacements recorded south and southwest of the epicenter. However, the waveform coherency observed across an array south and southwest of the epicenter suggests that the rupture length is less than 6 km. The maximum dislocation is about 120 cm in a small area near the hypocenter and the total moment is estimated to be 3.5 x 1024 dyne-cm. An abrupt stopping phase, which corresponds to a cessation of right-lateral motion, can explain the high peak acceleration recorded at array station 6. The stress drop in the hypocentral area is about 140 bars; although the average stress drop over the entire rupture surface is 30 bars. This preferred finite source model can predict observed Pni waveforms as well as the beginning features of teleseismic body waves.
\r\n\r\nIn part 1-B, a similar waveform modeling technique is used to interpret the ground motions recorded during the June 28, 1966 Parkfield earthquake. The preferred model suggests that the earthquake involved two fault segments; one is the NE branch which extends 22 km southward from epicenter and has an average slip of 45 cm, another is the SW branch which ruptured less than 10 km and has an average slip of about 22 cm. The total moment indicated by this model is 1.25 x 1025 dyne-cm. The anomalous large amplitude ground displacement seen at station Cholame No. 2 is modeled as a local amplification effect rather than a source effect due to significant dislocation near this station.
\r\n\r\nDirect waveform comparisons between recordings of the Parkfield event and the Coyote Lake event also support the conclusion that the rupture length of the Coyote Lake earthquake is much shorter than that of the Parkfield event. The waveform modeling also emphasizes the importance of using array data to constrain source parameters. The solution derived from a single station's recording, which in many cases is the only available information, may often produce misleading results.
\r\n\r\nIn Chapter 2, high-frequency ground motions (ground velocity and acceleration) recorded at less than 30 km epicentral distances are studied for two aftershocks of the 1979 Imperial Valley, California earthquake. In the past, little has been done to understand these high frequency waves through a deterministic modeling approach. The waveform modeling technique and the source mechanisms of these two aftershocks are described in sections 2-A and 2-B.
\r\n\r\nAn important feature of the ground motions recorded during the October 15, 1979 Imperial Valley earthquake sequence is the strong high frequency waves observed on the vertical components. This feature is also seen in recordings of the aftershock of October 16, 23:16, 1979, which is described in section 2-A. This polarization feature is easily explained by the basin velocity structure which bends rays towards the vertical at the free surface. Short S-P times are observed at the three closest stations (epicentral distances of 3 km to 5 km) suggesting that this aftershock occurred at a very shallow depth of about 2 km. A fault plane orientation (strike = N20\u00b0E, dip = 30\u00b0SE, and rake = -80\u00b0) obtained from a first P-motion study, generates synthetic waveforms of the strong ground velocities which are similar to those observed at three closest stations. The source time duration is determined to be 1.0 second and the moment is 1.6x1023 dyne-cm. Synthetics for a number of line source models are compared with the observations. These comparisons lead to two basic mechanisms that are necessary to explain the frequency content of the observed P- and S- waves. One is that the source process is characterized by irregular rupture. It is postulated that the heterogeneous stiffness in the layered medium is the basic cause of the irregular rupture. Heterogeneous rupture generates both high-frequency P- and S-waves. In order to explain the contrast in observed frequency content it is also necessary that there is a mechanism for attenuating S-waves much stronger than P-waves.
\r\n\r\nThe aftershock that occurred about 3 minutes after the mainshock, at 23:19 October 15, 1979 is presented in section 2-B. This aftershock was located on the Imperial fault near Highway 8 and close to the zone of high frequency energy release of the main event. The impulsive seismograms for 16 array stations, ranging from 8 km to 26 km in epicentral distance, are well suited for source parameter inversion studies to obtain an optimal solution for ground velocity and acceleration. The earthquake source is approximated by a model consisting of several point dislocation sources separated in space and time and having different dislocation orientations and moments. These source parameters were deduced by trial and error modeling as well as by applying inversion procedures. The waveforms and amplitudes of horizontal ground velocities are well modeled by two predominantly strike-slip point sources; the first source (strike = N41\u00b0W, dip = 42\u00b0NE and rake = 174\u00b0) has a moment of 0.7 x 1024 dyne-cm, the second source (strike = N36\u00b0W, dip = 82\u00b0SW and rake = 181\u00b0) lies about 1 km to the north of the first and has a seismic moment of about twice that of the first source. It is suggested that the higher-frequency ground motions, such as accelerations, can be derived from very irregular source processes, whereas the longer-period ground motions, such as ground displacements, can be well modeled by simpler planar source.
\r\n\r\nA Futterman attenuation operator with a t*\u03b2 of about 0.08 to 0.1 and a t*\u03b1 of about 0.001 in the sedimentary region produces longer period S waves and the proper amplitude ratio between P and S waves.
\r\n\r\nIn Chapter 3, the ground motion data from the 1971 San Fernando earthquake recorded at epicentral distances of less than 100 km are presented. Three long profiles (> 50 km ) and three short profiles (< 2 km) of ground velocity and acceleration, displayed as a function of epicentral distance are analyzed.
\r\n\r\nAlthough there is considerable variation in waveforms and peak amplitudes observed along the long profiles, there are also many examples of coherent phases seen at adjacent stations. Ground velocity profiles show striking differences in amplitude and duration between stations located on hard rock sites and stations located within the sedimentary basins. The San Fernando basin, in which the source is located, seems to respond quite differently from the Los Angeles basin which is about 30 km from the earthquake source area. Ground acceleration profiles show that there is little change in the duration of high-frequency shaking along the long profiles.
\r\n\r\nThe three short profiles, which are all located within the Los Angeles basin, demonstrate that ground velocity waveforms are nearly identical along these profiles. Although greater variation of waveforms and amplitudes are seen for ground acceleration along these short profiles, strong phase coherence is still observed.
\r\n\r\nThe 2D acoustical finite difference method is used to compute the effects on SH-waves of irregular velocity structures believed to exist along Profile I and Profile II. Profile I extends 65 km southward from the epicenter across the San Fernando and Los Angeles basins to a station on the Palos Verdes Peninsula. Profile II extends 95 km S 40\u00b0 E along the front of the San Gabriel mountains and across the San Gabriel and Los Angeles basins. These numerical models consist of low-velocity sedimentary basins (\u03b2 = 2.1 km/sec) of irregular shape which are imbedded in high-velocity basement rock (\u03b2 = 3.5 km/sec). Heaton's (1982) finite source model derived from modeling the five nearest stations for the San Fernando event, is also incorporated in the interpretation. The resulting simulation suggests that the smaller S! phases in both Profile I and Profile II are direct S waves from the deep source region (13 km). The shallow source region (at 1 km) dominates high amplitude later arrived phases observed along Profile I and are due to the complicated basin path along this profile. The shallower source region, however, contributes little to the ground motions along Profile II due to the lack of thick sediments near the source region along this azimuth.
", "doi": "10.7907/5hbj-fd95", "publication_date": "1983", "thesis_type": "phd", "thesis_year": "1983" }, { "id": "thesis:10896", "collection": "thesis", "collection_id": "10896", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05162018-100416743", "type": "thesis", "title": "Experimental Observations of the Effect of Foundation Embedment on Structural Response", "author": [ { "family_name": "Lin", "given_name": "Albert Niu", "clpid": "Lin-Albert-Niu" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" }, { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "Ambient, ring-down, and forced vibration tests were used to determine the effect of foundation embedment on the response of a one-story model structure 10 ft square in plan and 11.4 ft high. The tests, conducted at the full-, half- and unembedded foundation conditions, led to the identification of the fundamental translatory mode in the primary (east-west) and secondary (north-south) directions, and two torsional modes. The forced vibration consisted of horizontally incident SH-waves generated at an excitation structure located 47.5 ft (center-to-center) away. During these tests, detailed measurements of the near-field ground motion and modal displacement ratios were obtained at the fundamental mode in the primary direction. The displacement ratios were used to calculate the structural and foundation-soil stiffnesses and damping coefficients for comparison to theoretical results. Foundation embedment increased the model frequencies and decreased the contribution of the foundation motion to the overall displacement of the superstructure. For the fundamental mode response, which consisted of translatory and rocking motions, the resonant frequency predicted by lumped parameter analysis was higher than that measured experimentally by 25% for the unembedded case. While the experimental and theoretical fundamental mode shapes were in close agreement, the calculated effect of embedment on the response was less than that measured. These results were consistent with the comparison of the impedances and embedment factors. Serious discrepancies between analytical and experimental results were found for the case of torsion; a simple two-degree-of-freedom model was consistent only with the first of the two measured resonant frequencies.
", "doi": "10.7907/ksr8-pf30", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:10901", "collection": "thesis", "collection_id": "10901", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05162018-151856693", "type": "thesis", "title": "Dynamic Behavior of Rocking Structures Allowed to Uplift", "author": [ { "family_name": "Psycharis", "given_name": "Ioannis N.", "clpid": "Psycharis-Ioannis-N" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Marble", "given_name": "Frank E.", "clpid": "Marble-F-E" }, { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Strong shaking of structures during large earthquakes may result in some cases in partial separation of the base of the structure from the soil. This phenomenon of uplifting, which can affect the dynamic behavior of the structure significantly, even if the amount of uplift is small, is examined in this thesis. First the case of a rocking rigid block is investigated and then more complicated, flexible superstructures are introduced. Two foundation models which permit uplift are considered: the Winkler foundation and the much simpler \"two-spring\" foundation. Several energy dissipating mechanisms are also introduced into these models. It is shown that an equivalence between these two models for the foundation can be established, so that one can always work with the much simpler two-spring foundation. In this way complete analytical solutions can be derived in most cases. Moreover, simple approximate methods for the calculation of the apparent fundamental period of the rocking system are developed and simplified methods of analysis are proposed.
\r\n\r\nIn general, uplift leads to a softer vibrating system which behaves nonlinearly, although the response is composed of a sequence of linear responses. As a result, the apparent fundamental resonant frequency of the uplifting system is always less than the fundamental resonant frequency of both the soil-structure interacting system, in which lift-off is not allowed, and the superstructure itself. The second and higher resonant frequencies of the superstructure, however, are not affected significantly by lift-off. For damped foundations, the ratio of critical damping associated with the apparent fundamental mode decreases, in general, with the amount of lift-off. These effects of uplift on the dynamic properties of the rocking system can alter the response of the structure significantly during an earthquake. Nevertheless, it cannot be said a priori whether they are favorable to the behavior or not; this depends on the parameters of the system and the time history of the excitation.
", "doi": "10.7907/jexq-jr68", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:4982", "collection": "thesis", "collection_id": "4982", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-12132006-104119", "type": "thesis", "title": "Dynamic Centrifuge Testing of Cantilever Retaining Walls", "author": [ { "family_name": "Ortiz", "given_name": "Louis Alexander", "clpid": "Ortiz-Louis-Alexander" } ], "thesis_advisor": [ { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "thesis_committee": [ { "family_name": "Beck", "given_name": "James L.", "clpid": "Beck-J-L" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Knowles", "given_name": "James K.", "clpid": "Knowles-J-K" }, { "family_name": "Scott", "given_name": "Ronald F.", "clpid": "Scott-R-F" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "An investigation was made into the behavior of flexible cantilever walls retaining a cohesionless soil backfill and subjected to earthquake-type dynamic excitations using the centrifuge modelling technique. The study was motivated by the abundant observations of earth retaining structure damage and failures documented in earthquake damage reports.
\r\n\r\nThe \"prototype\" typical walls were designed using the traditional Mononobe-Okabe dynamic lateral earth pressure theory, were properly scaled for use in the centrifuge at 50 g's and were subjected to lateral earthquake-like motions which were considered to be of realistic levels. The walls were amply instrumented with pressure and displacement transducers, accelerometers, and strain gages. Moment, pressure, shear, and displacement distributions (static, dynamic, and residual) were obtained.
\r\n\r\nFrom the test data, some empirical curves for relating the upper bound responses of the retaining walls to the strong motion characteristics of the applied earthquakes were obtained.
", "doi": "10.7907/vep9-1127", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:5064", "collection": "thesis", "collection_id": "5064", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-12192006-152351", "type": "thesis", "title": "Prediction of Flow Depth and Sediment Discharge in Open Channels", "author": [ { "family_name": "Brownlie", "given_name": "William Robert", "clpid": "Brownlie-William-Robert" } ], "thesis_advisor": [ { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" } ], "thesis_committee": [ { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Koh", "given_name": "Robert C. Y.", "clpid": "Koh-R-C-Y" }, { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" }, { "family_name": "Vanoni", "given_name": "Vito A.", "clpid": "Vanoni-V-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In recent years attempts have been made to develop numerical models for unsteady flows in channels with sediment transport. This work was conducted to analyze two essential ingredients of any numerical model: the relationship between the hydraulic variables (slope, depth, and velocity), and the predictor of sediment concentration.
\r\n\r\nA data base containing 7027 records (5263 laboratory records and 1764 field records) in 77 data files was assembled and is provided (Appendix B). The data base was used to examine existing relationships and to develop new ones. Six existing hydraulic relationships are reworked and examined. Detailed statistical analyses are provided for 13 existing techniques for predicting sediment concentration.
\r\n\r\nRelying heavily on statistical analysis of dimensionless groups, new relationships have been developed. The new hydraulic relationship solves for flow depth for upper and lower regime flow separately and then provides a method for determining which flow regime one might expect. The new method for predicting sediment transport, which is easy to use, appears to be more accurate than the 13 existing methods, and suggests that complex procedures for calculating concentration are not warranted.
\r\n\r\nA four-point implicit finite difference scheme has been presented to demonstrate the feasibility of applying the new hydraulic and sediment relationships to a numerical solution of the differential equations.
", "doi": "10.7907/100Z-Z157", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:3460", "collection": "thesis", "collection_id": "3460", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09112006-130749", "type": "thesis", "title": "Finite Element Formulations for Hyperbolic Systems with Particular Emphasis on the Compressible Euler Equations", "author": [ { "family_name": "Tezduyar", "given_name": "Tayfun Ersin", "clpid": "Tezduyar-Tayfun-Ersin" } ], "thesis_advisor": [ { "family_name": "Wu", "given_name": "Theodore Yao-tsu", "clpid": "Wu-T-Y-T" } ], "thesis_committee": [ { "family_name": "Sabersky", "given_name": "Rolf H.", "clpid": "Sabersky-R-H" }, { "family_name": "Corngold", "given_name": "Noel Robert", "clpid": "Corngold-N-R" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Hughes", "given_name": "Thomas J. R.", "clpid": "Hughes-T-J-R" }, { "family_name": "Wu", "given_name": "Theodore Yao-tsu", "clpid": "Wu-T-Y-T" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "A Petrov-Galerkin finite element formulation for first-order hyperbolic systems is developed generalizing the streamline approach which has been successfully applied previously to convection-diffusion and incompressible Navier-Stokes equations. The formulation is shown to possess desirable stability and accuracy properties.
\r\n\r\nThe algorithm is applied to the Euler equations in conservation-law form and is shown to be effective in all cases studied, including ones with discontinuous solutions. Accurate and crisp representation of shock fronts in transonic problems is achieved.
", "doi": "10.7907/994z-vj07", "publication_date": "1982", "thesis_type": "phd", "thesis_year": "1982" }, { "id": "thesis:241", "collection": "thesis", "collection_id": "241", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01192007-153149", "type": "thesis", "title": "Tsunamis \u2013 Harbor Oscillations Induced by Nonlinear Transient Long Waves", "author": [ { "family_name": "Lepelletier", "given_name": "Thierry Georges", "clpid": "Lepelletier-Thierry-Georges" } ], "thesis_advisor": [ { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" } ], "thesis_committee": [ { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Kanamori", "given_name": "Hiroo", "orcid": "0000-0001-8219-9428", "clpid": "Kanamori-H" }, { "family_name": "Wu", "given_name": "Theodore Yao-tsu", "clpid": "Wu-T-Y-T" }, { "family_name": "Raichlen", "given_name": "Fredric", "clpid": "Raichlen-F" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The process of excitation of harbors and bays by transient nonlinear long waves is investigated theoretically and experimentally. In addition, nonlinear shallow water waves generated in a closed rectangular basin by the motion of the basin are also examined.
\r\n\r\nTwo numerical methods based on finite element techniques are used to solve the weakly nonlinear-dispersive-dissipative equations of motion and are applied to the basin excitation problem and the transient harbor oscillation problem, respectively. In the latter case, the open sea conditions are simulated by including a radiative boundary condition in time at a finite distance from the harbor entrance. Various dissipative effects are also included. In addition to the numerical results, analytical solutions are presented to investigate certain particular aspects of basin and harbor oscillations (e.g., the effects of viscous dissipation in a harbor with simple geometry).
\r\n\r\nExperiments conducted in the closed rectangular basin indicate that for a continuous excitation at or near a resonant mode of oscillation the linear theory becomes inadequate and the nonlinear-dispersive-dissipative theory must be used. For a transient excitation the validity of the linear theory depends on the value of the Stokes parameter. Indeed, some features not predicted by the linear theory can be directly inferred from the magnitude of this parameter.
\r\n\r\nExperiments on the continuous wave induced oscillations of a narrow rectangular harbor with constant depth show that at the first resonant mode convective nonlinearities can be neglected and a linear dissipative solution is sufficient to describe the waves inside the harbor. At the second resonant mode which corresponds to a longer harbor relative to the length of the incident wave, nonlinear convective effects become important and must be incorporated into the numerical model. Also the characteristics of various sources of dissipation which reduce resonance in the harbor are investigated experimentally. The sources considered include, among others, laminar boundary friction, leakage losses underneath the harbor walls, and energy dissipation due to flow separation at the entrance of the harbor.
\r\n\r\nThe good agreement obtained between the experiments and the nonlinear numerical model developed in this study suggests that this model could be used with some confidence to predict the response characteristics of prototype harbors. As an example, the results of this study have been applied to the response of Ofunato Bay (Japan) to the tsunami generated by the Tokachi-Oki earthquake of May 16,1968. The model has been used to investigate the effects of convective nonlinearities on the bay oscillations and also to determine the efficiency of the breakwater which was built to reduce the effects of tsunamis at Ofunato.
\r\n", "doi": "10.7907/05TE-BH74", "publication_date": "1981", "thesis_type": "phd", "thesis_year": "1981" }, { "id": "thesis:4015", "collection": "thesis", "collection_id": "4015", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-10102006-110816", "primary_object_url": { "basename": "Liljestrand_hm_1980.pdf", "content": "final", "filesize": 4666320, "license": "other", "mime_type": "application/pdf", "url": "/4015/1/Liljestrand_hm_1980.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Atmospheric Transport of Acidity in Southern California by Wet and Dry Mechanisms", "author": [ { "family_name": "Liljestrand", "given_name": "Howard Michael", "clpid": "Liljestrand-Howard-Michael" } ], "thesis_advisor": [ { "family_name": "Morgan", "given_name": "James J.", "clpid": "Morgan-J-J" } ], "thesis_committee": [ { "family_name": "Morgan", "given_name": "James J.", "clpid": "Morgan-J-J" }, { "family_name": "Brooks", "given_name": "Norman H.", "clpid": "Brooks-N-H" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Anson", "given_name": "Fred C.", "clpid": "Anson-F-C" }, { "family_name": "Shair", "given_name": "Fredrick H.", "clpid": "Shair-F-H" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Acid precipitation samples collected at Pasadena, California, from February 1976 to April 1979 and at eight other southern California sites for shorter periods were analyzed to determine acid and base composition. The concentrations of major cations (H+, NH4+, Na+, K+, Ca2+, Mg2+) and anions (Cl-, NO2-, Br-, NO3-, SO42) as well as trace weak acids (Fe, Al, Mn, Si(OH)4, RCOOH) were determined. Titrations with base showed acidity predominantly to be due to strong acids (nitric and sulfuric) and weak acids (ammonium ion and carbonic acid). The pH was controlled by strong acidity at the urban sites in the Los Angeles Basin.\r\n\r\nThe chemical composition of precipitation samples collected in ~0.25 in increments is modeled in several ways. Chemical balances are used to determine the contributions of sea salt, soil dust, stationary sources, mobile sources and non-point sources of ammonia. Multiple regression analysis is used to relate ground-level measurements of air quality and atmospheric conditions with rainwater nitrite plus nitrate and sulfate concentrations. Precipitation intensity, ozone, nitric oxide and nitrogen dioxide concentrations are most strongly correlated with rainwater nitrite plus nitrate. Precipitation intensity, ozone, and nitric oxide are most strongly correlated with rainwater sulfate.\r\n\r\nGas-liquid equilibrium models yield the following predictions: Low partial pressures of ammonia (average of 0.001 - 0.006 ppbv within the basin) during precipitation scavenging; total sulfite amounting to less than 25% of the non-sea salt sulfur; and nitrite concentrations from NO and NO2 dissolution which are slightly larger than observed values. Kinetic models of the formation of nitrate and sulfate underestimate the observed concentrations. Spatial distributions of acids and base correspond with local sources. The mountain sites and the more rural eastern sites have significantly less net acidity than the western urban sites.\r\n\r\nEstimates of the dry deposition of atmospheric acids indicate the dry flux is ~6600 equivalents/HA-YR in the Los Angeles Basin compared to ~380 equivalents/HA-YR for the wet flux of strong acidity. The semi-arid climate and high ambient pollutant concentrations cause the large dry flux. Advection of pollutants is the most important mechanism for the removal of acidity from the Los Angeles airshed.\r\n", "doi": "10.7907/pgev-yh86", "publication_date": "1980", "thesis_type": "phd", "thesis_year": "1980" }, { "id": "thesis:4611", "collection": "thesis", "collection_id": "4611", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-11212003-110242", "primary_object_url": { "basename": "Beck_jl_1979.pdf", "content": "final", "filesize": 15220041, "license": "other", "mime_type": "application/pdf", "url": "/4611/1/Beck_jl_1979.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Determining Models of Structures from Earthquake Records", "author": [ { "family_name": "Beck", "given_name": "James Leslie", "clpid": "Beck-James-Leslie" } ], "thesis_advisor": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "thesis_committee": [ { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" }, { "family_name": "Hudson", "given_name": "Donald E.", "clpid": "Hudson-D-E" }, { "family_name": "Wu", "given_name": "Theodore Yao-tsu", "clpid": "Wu-T-Y-T" }, { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "The problem of determining linear models of structures from seismic response data is studied using ideas from the theory of system identification. The investigation employs a general formulation called the output-error approach, in which optimal estimates of the model parameters are obtained by minimizing a selected measure-of-fit between the responses of the structure and the model. The question of whether the parameters can be determined uniquely and reliably in this way is studied for a general class of linear structural models. Because earthquake records are normally available from only a small number of locations in a structure, and because of measurement noise, it is shown that it is necessary in practice to estimate parameters of the dominant modes in the records, rather than the stiffness and damping matrices.
\r\n\r\nTwo output-error techniques are investigated. Tests of the first, an optimal filter method, show that its advantages are offset by weaknesses which make it unsatisfactory for application to seismic response. A new technique, called the modal minimization method, is developed to overcome these difficulties. It is a reliable and efficient method to determine the optimal estimates of modal parameters for linear structural models.
\r\n\r\nThe modal minimization method is applied to two multi-story buildings that experienced the 1971 San Fernando earthquake. New information is obtained concerning the properties of the higher modes of the taller building and more reliable estimates of the properties of the fundamental modes of both structures are found. The time-varying character of the equivalent linear parameters is also studied for both buildings. It is shown for the two buildings examined that the optimal, time-invariant, linear models with a small number of modes can reproduce the strong-motion records much better than had been supposed from previous work using less systematic techniques.
", "doi": "10.7907/JP7R-KF57", "publication_date": "1979", "thesis_type": "phd", "thesis_year": "1979" }, { "id": "thesis:4694", "collection": "thesis", "collection_id": "4694", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-11302006-133224", "primary_object_url": { "basename": "Craig_je_1977.pdf", "content": "final", "filesize": 41710938, "license": "other", "mime_type": "application/pdf", "url": "/4694/1/Craig_je_1977.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Weak Shocks in Open-Ended Ducts with Complex Geometry", "author": [ { "family_name": "Craig", "given_name": "James Eldon", "clpid": "Craig-James-Eldon" } ], "thesis_advisor": [ { "family_name": "Sturtevant", "given_name": "Bradford", "clpid": "Sturtevant-B" } ], "thesis_committee": [ { "family_name": "Sturtevant", "given_name": "Bradford", "clpid": "Sturtevant-B" }, { "family_name": "Roshko", "given_name": "Anatol", "clpid": "Roshko-A" }, { "family_name": "Culick", "given_name": "Fred E. C.", "clpid": "Culick-F-E-C" }, { "family_name": "Whitham", "given_name": "Gerald Beresford", "clpid": "Whitham-G-B" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" } ], "local_group": [ { "literal": "GALCIT" }, { "literal": "div_eng" } ], "abstract": "The dynamics of weak shocks in ducts of complex geometry and the sound radiation produced by the reflection of a weak shock from the open end of a duct have been investigated. Duct geometries include expansion chambers with and without inlet or outlet tubes extended and enclosed perforated tubes. Internal and external pressure histories of the interaction of weak shocks with simple muffler elements have been recorded using a standard one-shot shock tube and a resonating shock tube. The excitation shock Mach number ranged from 1.05 to 1.55. Analytical investigations, including a synthesis of existing works on internal weak-shock interactions of an acoustic treatment of the sound radiation produced by weak shock waves, are presented. Combining the above analyses, models for the reduction in radiated sound per unit of incident shock amplitude, as a result of inserting a muffler between the source and the tailpipe exit, are developed.\r\n\r\nFor expansion chambers with and without extensions, the dependence of the transmitted and reflected waves and of the radiated sound on area ratio is compared with predictions. In particular, measured transmission coefficients for expansion chambers agree reasonably well with the predictions for all shock strengths; however, for large area ratios, the predicted sound attenuation is not observed, as waves diffracted at the upstream junction cause more sound to be radiated. For expansion chambers with internal extensions, sound attenuation is increased for low incident shock strengths; while for increasing incident shock strength, the internal transmission characteristics deteriorate, the reducing the sound attenuation.\r\n\r\nFor enclosed perforated tubes, the dependence of the transmitted and reflected waves and of the radiated sound on the perforated area ratio and incident shock strength is compared with predictions. For perforated tubes with infinite enclosure, the transmission and reflection coefficients depend on both incident shock strength and perforated area ratio, as predicted. However, agreement with data is obtained only after inserting a perforated discharge coefficient with the perforated area ratio in the theory. The reduction of sound radiation with perforated area ratio is measured for one incident shock strength and then compared with predictions. For small area ratios, there is agreement but for large area ratios the measurements show that less sound is radiated than predicted. For large area ratios, gradual compressions with smooth fronts (not shock fronts) are transmitted, resulting in less radiated sound. Enclosures have no effect on the sound attenuation for small perforate area ratios; however, as the perforate area ratio increases, the enclosure eventually inhibits further increase in sound attenuation.", "doi": "10.7907/QAFR-PS29", "publication_date": "1977", "thesis_type": "phd", "thesis_year": "1977" }, { "id": "thesis:10741", "collection": "thesis", "collection_id": "10741", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03012018-135434228", "type": "thesis", "title": "Dynamic Analyses of Suspension Bridge Structures and Some Related Topics", "author": [ { "family_name": "Abdel-Ghaffar", "given_name": "Ahmed Mansour", "clpid": "Abdel-Ghaffar-Ahmed-Mansour" } ], "thesis_advisor": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" } ], "thesis_committee": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Iwan", "given_name": "Wilfred D.", "clpid": "Iwan-W-D" }, { "family_name": "Marble", "given_name": "Frank E.", "clpid": "Marble-F-E" }, { "family_name": "Babcock", "given_name": "Charles D.", "clpid": "Babcock-C-D" }, { "family_name": "Munger", "given_name": "Edwin S.", "clpid": "Munger-Edwin-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The thesis is divided into two parts. The first part develops a method of dynamic analysis for vertical, torsional and lateral free vibrations of suspension bridges, based on linearized theory and the finite-element approach. The method involves two distinct steps: (1) specification of the potential and kinetic energies of the vibrating members of the continuous structure, leading to derivation of the equations of motion by Hamilton's Principle, (2) use of the finite-element technique to: (a) discretize the structure into equivalent systems of finite elements, (b) select the displacement model most closely approximating the real case, (c) derive element and assemblage stiffness and inertia properties, and finally (d) form the matrix equations of motion and the resulting eigenvalue problems. The stiffness and inertia properties are evaluated by expressing the potential and kinetic energies of the element (or the assemblage) in terms of nodal displacements. Detailed numerical examples are presented to illustrate the applicability and effectiveness of the analysis and to investigate the dynamic characteristics of suspension bridges with widely different properties. This method eliminates the need to solve transcendental frequency equations, simplifies the determination of the energy stored in different members of the bridge, and represents a simple, fast and accurate tool for calculating the natural frequencies and modes of vibration by means of a digital computer. The method is illustrated by calculating the modes and frequencies of a bridge and comparing them with the measured frequencies.
\r\n\r\nThe second part contains two studies on the effect of differential motions of two foundations upon the response of the superstructure of a bridge. The first study deals with the dynamic response of a \"long beam\" model of a bridge to both steady-state and random excitations applied at the supports. The second study develops a method to analyze the dynamic soil-bridge interaction of a simple bridge model erected on an elastic half-space, and the input motion is in the form of incident plane SH-waves. The dynamic response of the bridge and the effect of the radiative damping in the half-space on the interaction of the bridge are also studied.
", "doi": "10.7907/Y1XR-WG52", "publication_date": "1976", "thesis_type": "phd", "thesis_year": "1976" }, { "id": "thesis:10573", "collection": "thesis", "collection_id": "10573", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11302017-155936522", "type": "thesis", "title": "Response and Failure of Structures Under Stationary Random Excitation", "author": [ { "family_name": "Adu", "given_name": "Randolph Ademola", "clpid": "Adu-Randolph-Ademola" } ], "thesis_advisor": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" } ], "thesis_committee": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "De Prima", "given_name": "Charles R.", "clpid": "De-Prima-C-R" }, { "family_name": "Hudson", "given_name": "Donald E.", "clpid": "Hudson-D-E" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Vreeland", "given_name": "Thad", "clpid": "Vreeland-T" } ], "local_group": [ { "literal": "Earthquake Engineering Research Laboratory" }, { "literal": "div_eng" } ], "abstract": "The response of simple structural systems to stationary random excitation is considered under two criteria of failure. When failure is specified as the crossing of a maximum tolerable threshold by the response, the reliability of a structure is commonly measured by means of response spectra. These give the expected maximum value of the response parameter for a given excitation level. The statistical variations in these spectra are obtained here for viscously damped linear and elastoplastic single-degree of freedom systems by electronic analog simulation. The results obtained are compared with approximate statistical analyses; for example, the threshold crossing statistics of narrow-band oscillators. It is concluded that such methods give satisfactory, but conservative, estimates of the mean spectral values. It is significant that all the spectra obtained showed a very wide distribution about the mean. This was also true of the Fourier amplitude spectrum of the excita\u00adtion.
\r\n\r\nFor response that are so large that structures actually collapse, the linear model was replaced by an elastoplastic system, and the effect of gravity on the collapse time was considered. Experimental simulation showed that the structural response in this case is essentially that of a linear oscillator with yielding occurring at intermittent intervals. Gravity acts to increasingly bias this yielding in one direction, eventually causing instability in the system. Collapse of the system was sensitive to the distribution of peaks in the excitation and it was found that the wide dispersion in the collapse time can be reasonably represented by a Gamma distribution function.
\r\n\r\nAn analytic method for estimating the mean collapse time was derived by considering the energy distribution of the excitation and its effect on the yielding of the structure. The response process was thus modelled by that of an equivalent linear oscillator whose baseline is biased by the yielding in the structure. It was concluded that this procedure gives a good estimate of the failure time for excitations strong enough to cause failure in less than 20 seconds.
\r\n\r\nA two-degree of freedom elastoplastic hysteretic system with gravity was also simulated. In a certain sense, the qualitative behavior is similar to that of the single-degree of freedom system. It was thus possible to estimate the failure time of the structure from that of a single-degree of freedom system once the transmission of vibration is accounted for by considering a linear two-degree of freedom system.
", "doi": "10.7907/6304-3X27", "publication_date": "1971", "thesis_type": "phd", "thesis_year": "1971" }, { "id": "thesis:3653", "collection": "thesis", "collection_id": "3653", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09202002-143339", "primary_object_url": { "basename": "Husid_r_1967.pdf", "content": "final", "filesize": 7372125, "license": "other", "mime_type": "application/pdf", "url": "/3653/1/Husid_r_1967.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Gravity Effects on the Earthquake Response of Yielding Structures", "author": [ { "family_name": "Husid", "given_name": "Ra\u00fal", "clpid": "Husid-Ra\u00fal" } ], "thesis_advisor": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Hudson", "given_name": "Donald E.", "clpid": "Hudson-D-E" } ], "thesis_committee": [ { "family_name": "Housner", "given_name": "George W.", "clpid": "Housner-G-W" }, { "family_name": "Jennings", "given_name": "Paul C.", "clpid": "Jennings-P-C" }, { "family_name": "Hudson", "given_name": "Donald E.", "clpid": "Hudson-D-E" }, { "family_name": "Caughey", "given_name": "Thomas Kirk", "clpid": "Caughey-T-K" }, { "family_name": "Franklin", "given_name": "Joel N.", "clpid": "Franklin-J-N" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The effect of gravity on the earthquake response of one degree of freedom yielding structures is studied by subjecting them to earthquake-like excitation. Interest is centered on the time required for yielding to progress to the point of collapse. The results show that the effect of gravity is to increase significantly the development of permanent set over that occurring when gravity is ignored. Because the gravity effect increases as the deflection grows, the permanent set increases rapidly just prior to failure.\r\n\r\nA statistical study of the time to failure for elasto-plastic structures indicates that the average time to failure is inversely proportional to the square of the ratio of the earthquake strength to the lateral yield level of the structure, implying that an earthquake of short duration would have to possess significantly higher accelerations than a longer earthquake in order to cause failure of a given structure.\r\n\r\nIt was found that for the range of periods considered the average time to collapse for the yielding structures was independent of period. For the bilinear hysteretic structure the results show a large increase in the time of failure when the second slope increases from zero.\r\n\r\nCalculations made with simultaneous vertical and horizontal excitation, and with recorded strong earthquake accelerograms, indicate that the thesis results, obtained from artificial earthquakes, should be applicable for strong earthquake excitation.\r\n\r\nComparison of the results with those of a one-dimensional random walk indicates that on the average a yielding structure will collapse after the input of a certain amount of energy.", "doi": "10.7907/9XAB-6V59", "publication_date": "1967", "thesis_type": "phd", "thesis_year": "1967" } ]