Three Dimensional Nonlinear Seismic Response Of Large Scale Ground Structure Systems
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Three Dimensional Nonlinear Seismic Response Of Large Scale Ground Structure Systems
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Author : Kyung Tae Kim
language : en
Publisher:
Release Date : 2014
Three Dimensional Nonlinear Seismic Response Of Large Scale Ground Structure Systems written by Kyung Tae Kim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Effort is geared towards development of large-scale nonlinear ground-structure seismic response simulations. Mechanisms to allow for modeling of transmitting boundaries are incorporated, mainly relying on the Domain Reduction Method (DRM) approach. Parallel computing is employed to permit the execution of these large-scale simulations. A range of geometric configurations are addressed in order to explore various aspects of the involved seismic response characteristics. The OpenSees computational platform is employed throughout. To accommodate nonlinear response and soil/structure element stiffness considerations, an implicit time integration scheme is adopted. This scheme poses severe limitations on the number of parallel computing processors that can be used with reasonable efficiency (due to the required taxing communications between the different processors). Within the available constraints on time and computing resources, and the necessary additional OpenSees parallel-implementation machine-specific adaptions, the conducted DRM investigations mostly employed a soil domain 3D 8-node brick element of a 20 m side length (with about 150,000 such elements in the mesh). Consequently, severe limitations are imposed on the frequency content of the propagated seismic waves and the resulting system response. Future extensions in this direction of research can build solidly on the developments in this report and provide more accurate higher frequency system response. Significant attention is given to the simulation of a large-scale highway interchange system under seismic loading. A three-dimensional (3D) Finite Element model of an existing bridge interchange at the intersection of Interstates 10 and 215 (San Bernardino, CA) is developed. This interchange consists of three connectors at different bridge superstructure elevations. Initial focus is placed on modeling the three bridges, evaluation of vibration properties, and validation of one of the bridge models (North-West connector, NW) based on available earlier recorded earthquake response. A strategy to incorporate the above bridge structural models into a bridge-foundation-ground system (BFGS) is implemented based on the Domain Reduction Method (DRM) as developed by Bielak and his co-workers. A numerical implementation of this DRM by Petropolous and Fenves is employed and adapted as the soil domain. In this implementation, seismic waves are propagated from a realistic fault rupture scenario in southern California. As such, the BFGS can include the three-bridge interchange subjected to a 3D seismic excitation scenario. Within this numerical analysis framework, the effect of foundation soils of different stiffness and strength are investigated. The results are compared to the more conventional bridge model response under uniform as well as multi-support base excitation. In addition to this DRM-based implementation, a nonlinear ground-bridge model based on the actual local soil conditions at the interchange is investigated (with the NW only as the super-structure). Efforts include implementation and validation of a classical transmitting boundary at the base of the soil domain. Using this formulation, the BFGS response is compared and validated with earthquake recorded response at the bridge and local site. Under a potential site specific strong ground motion, computed force demands from the employed linear column models are compared to the strength as defined by a representative nonlinear column formulation. Finally, the seismic response of a large rigid structure with different embedment depths is assessed. Dynamic interaction between the structure and the surrounding soil is studied based on changes in soil elastic properties, depth of embedment, and characteristics of input excitation.
Seismic Response Of Large Embedded Structures And Soil Structure Interaction
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Author : John Li
language : en
Publisher:
Release Date : 2019
Seismic Response Of Large Embedded Structures And Soil Structure Interaction written by John Li and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
For large relatively stiff structures, soil structure interaction (SSI) plays a major role in dictating the overall seismic response. In light of recent strong seismic excitation affecting such structures, three-dimensional response as well as nonlinear soil behavior are among the areas of increased interest. As such, a series of numerical studies are conducted to shed more light on the involved SSI mechanisms. Amongst those studies is a comparison of the equivalent linear and nonlinear soil formulations in evaluating the seismic response of large embedded structures. Depending on the level of attained nonlinear response, influence of the following modeling considerations is discussed: i) employing the nonlinear versus linear soil formulation, ii) initial own-weight lateral earth pressure stress-state, and iii) the soil-structure interface characteristics. Both formulations generally resulted in remarkably close estimates of structural response. An opportunity to investigate the SSI mechanisms of large embedded structures due to low amplitude shaking was permitted by the availability of seismic data from an instrumented test site at Higashi-dori, Japan. The compiled data set includes the recorded accelerations, for two downhole arrays, and the response of a 1/10th scale twin reactor. The extracted site properties are shown to provide a reasonable match to the recorded data. Using these properties parametric computational studies are conducted to illustrate salient mechanisms associated with the seismic response of such large embedded structural systems. Furthermore, an opportunity to investigate the seismic response of the Fukushima nuclear reactors due to strong shaking was facilitated by data recorded during the magnitude 9.1 Tōhoku earthquake. Linear and nonlinear response of the ground was evaluated using system identification techniques. During the strong shaking, a clear and significant reduction in stiffness was observed within the upper soil strata. Of special interest was the response of Unit 6, which was the most heavily instrumented of the reactors. Response at the base of Unit 6 was compared to that of the nearby downhole array. Amplification of motion along the height of Unit 6 was evaluated, exhibiting the primary role of rocking response.
Methods Computational Platform Verification And Application Of Earthquake Soil Structure Interaction Modeling And Simulation
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Author : Nima Tafazzoli
language : en
Publisher:
Release Date : 2012
Methods Computational Platform Verification And Application Of Earthquake Soil Structure Interaction Modeling And Simulation written by Nima Tafazzoli and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Seismic response of soil-structure systems has attracted significant attention for a long time. This is quite understandable with the size and the complexity of soil-structure systems. The focus of three important aspects of ESSI modeling could be on consistent following of input seismic energy and a number of energy dissipation mechanisms within the system, numerical techniquesused to simulate dynamics of ESSI, and influence of uncertainty of ESSI simulations. This dissertation is a contribution to development of one such tool called ESSI Simulator. The work is being done on extensive verified and validated suite for EESI Simulator. Verification and validation are important for high fidelity numerical predictions of behavior of complex systems. This simulator uses finite element method as a numerical tool to obtain solutions for large class of engineering problems such as liquefaction, earthquake-soil-structure-interaction, site effect, piles, pile group, probabilistic plasticity, stochastic elastic-plastic FEM, and detailed large scale parallel models. Response of full three-dimensional soil-structure-interaction simulation of complex structures is evaluated under the 3D wave propagation. Domain-Reduction-Method is used for applying the forces as a two-step procedure for dynamic analysis with the goal of reducing the large size computational domain. The issue of damping of the waves at the boundary of the finite element models is studied using different damping patterns. This is used at the layer of elements outside of the Domain-Reduction-Method zone in order to absorb the residual waves coming out of the boundary layer due to structural excitation. Extensive parametric study is done on dynamic soil-structure-interaction of a complex system and results of different cases in terms of soil strength and foundation embedment are compared. High efficiency set of constitutive models in terms of computational time are developed and implemented in ESSI Simulator. Efficiency is done based on simplifying the elastic-plastic stiffness tensor of the constitutive models. Almost in all the soil-structure systems, there are interface zones in contact with each other. These zones can get detached during the loading or can slip on each other. In this dissertation the frictional contact element is implemented in ESSI Simulator. Extended verification has been done on the implemented element. The interest here is the effect of slipping and gap opening at the interface of soil and concrete foundation on the soil-structure system behavior. In fact transferring the loads to structure is defined based on the contact areas which will affect the response of the system. The effect of gap openings and sliding at the interfaces are shown through application examples. In addition, dissipation of the seismic energy due to frictional sliding of the interface zones are studied. Application Programming Interface (API) and Domain Specific Language (DSL) are being developed to increase developer's and user's modeling and simulation capabilities. API describes software services developed by developers that are used by users. A domain-specific language (DSL) is a small language which usually focuses on a particular problem domain in software. In general DSL programs are translated to a common function or library which can be viewed as a tool to hide the details of the programming, and make it easier for the user to deal with the commands.
A Quantitative Seismic Behavior Assessment Of Buried Structures
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Author : Wenyang Zhang
language : en
Publisher:
Release Date : 2019
A Quantitative Seismic Behavior Assessment Of Buried Structures written by Wenyang Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
This dissertation is focused on quantitatively investigating the nonlinear seismic behavior assessment of underground structures, by performing high-fidelity SSI analyses. Specifically, several computer codes are developed for forward simulation of wave propagation in both two- (plane-strain) and three-dimensional semi-infinite heterogeneous solid media. (i) a multi-axial bounding surface plasticity model is implemented, calibrated and validated through centrifuge test data, to consider the soil nonlinearities (ii) the domain reduction method (DRM) is implemented for both 2D and 3D domains, homogeneous and heterogeneous media, vertical and inclined incident SV waves, to consistently prescribe the input motions in a truncated domain and (iii) perfectly matched layer (PML) is implemented for both 2D and 3D domains, to absorb the outgoing waves super efficiently. By using the aforementioned numerical tools, multiple studies on seismic behavior assessment of underground structures are performed. 1. Development of validated methods for soil-structure analysis of buried structures. State-of-the-art versions of these simplified methods of seismic analysis for buried/embedded structures were most recently articulated in the "NCHRP 611" report, and comparisons of their predictions to experimental data are made in the present study in order to establish the validity (or lack thereof) of this method. Experiments comprises centrifuge tests on two specimens--one relatively- stiff rectangular and one relatively-flexible circular culvert--embedded in dense dry sand. Comparisons of experimental data are also made with predictions from a calibrated two-dimensional (plane-strain) finite element (FE) model. Predictions made using this FE model are superior and exhibits acceptable errors. 2. Parametric studies of buried circular structures and a proposed improvement of the NCHRP 611 method. The NCHRP 611 method has been widely adopted as a guideline in the analysis design of buried/embedded structures due to its computational simplicity and broadly accepted accuracy for simple soil-structure configurations. However, the method is not without shortcomings. In particular, the NCHRP method is not sensitive to the inherently broadband frequency content of seismic input excitations, soil heterogeneities, and potential kinematic interaction effects. The present study seeks to quantitatively assess the brackets of the validity of the NCHRP 611 method--specifically, for soil-structure analyses of buried circular structures, and offers an improvement that is simple to implement. This is achieved through parametric studies using detailed nonlinear finite element simulations involving a broad range of ground motions, and soil and structural properties. The simulations are carried out with a model that has been validated in a prior centrifuge testing program on embedded structures. A refined version of the NCHRP 611 method, which uses maximum shear strains obtained through one-dimensional site response analyses, is shown to produce fairly accurate results for nearly all of the different cases considered in the parametric studies. 3. Fragility-based seismic performance assessment of buried structures. Fragility-based seismic performance assessment and design procedures are being refined and adopted for many civil structures. With recent advances in computational capabilities as well as broad improvements in ground motion characterization and inelastic modeling of structural and geotechnical systems, large-scale direct models for underground structures--e.g., tunnels, water reservoirs, etc.--can now be devised with relative ease and deployed in engineering practice. In this study, a fragility-based seismic performance assessment of a large buried circular culvert is presented. Existing documents/codes are used to define the performance criteria and develop fragility functions through a Probabilistic Seismic Demand Analysis (PSDA) procedure. The analyses incorporate nonlinear behavior of soils and structural components, various soil layer profiles and account for uncertainties in the expected ground motions.
Earthquake Geotechnical Engineering Design
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Author : Michele Maugeri
language : en
Publisher: Springer Science & Business Media
Release Date : 2014-02-03
Earthquake Geotechnical Engineering Design written by Michele Maugeri and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-02-03 with Science categories.
Pseudo-static analysis is still the most-used method to assess the stability of geotechnical systems that are exposed to earthquake forces. However, this method does not provide any information about the deformations and permanent displacements induced by seismic activity. Moreover, it is questionable to use this approach when geotechnical systems are affected by frequent and rare seismic events. Incidentally, the peak ground acceleration has increased from 0.2-0.3 g in the seventies to the current value of 0.6-0.8 g. Therefore, a shift from the pseudo-static approach to performance-based analysis is needed. Over the past five years considerable progress has been made in Earthquake Geotechnical Engineering Design (EGED). The most recent advances are presented in this book in 6 parts. The evaluation of the site amplification is covered in Part I of the book. In Part II the evaluation of the soil foundation stability against natural slope failure and liquefaction is treated. In the following 3 Parts of the book the EGED for different geotechnical systems is presented as follows: the design of levees and dams including natural slopes in Part III; the design of foundations and soil structure interaction analysis in Part IV; underground structures in Part V. Finally in Part VI, new topics like the design of reinforced earth retaining walls and landfills are covered.
Single Piles In Liquefiable Ground
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Author : Rui Wang
language : en
Publisher: Springer
Release Date : 2016-03-17
Single Piles In Liquefiable Ground written by Rui Wang and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-03-17 with Science categories.
This thesis focuses on the seismic response of piles in liquefiable ground. It describes the design of a three-dimensional, unified plasticity model for large post-liquefaction shear deformation of sand, formulated and implemented for parallel computing. It also presents a three-dimensional, dynamic finite element analysis method for piles in liquefiable ground, developed on the basis of this model,. Employing a combination of case analysis, centrifuge shaking table experiments and numerical simulations using the proposed methods, it demonstrates the seismic response patterns of single piles in liquefiable ground. These include basic force-resistance mode, kinematic and inertial interaction coupling mechanism and major influence factors. It also discusses a beam on the nonlinear Winkler foundation (BNWF) solution and a modified neutral plane solution developed and validated using centrifuge experiments for piles in consolidating and reconsolidating ground. Lastly, it studies axial pile force and settlement during post-earthquake reconsolidation, showing pile axial force to be irrelevant in the reconsolidation process, while settlement is process dependent.
Challenges And Innovations In Geomechanics
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Author : Marco Barla
language : en
Publisher: Springer Nature
Release Date : 2021-01-14
Challenges And Innovations In Geomechanics written by Marco Barla and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-01-14 with Science categories.
This book gathers the latest advances, innovations, and applications in the field of computational geomechanics, as presented by international researchers and engineers at the 16th International Conference of the International Association for Computer Methods and Advances in Geomechanics (IACMAG 2020/21). Contributions include a wide range of topics in geomechanics such as: monitoring and remote sensing, multiphase modelling, reliability and risk analysis, surface structures, deep structures, dams and earth structures, coastal engineering, mining engineering, earthquake and dynamics, soil-atmosphere interaction, ice mechanics, landfills and waste disposal, gas and petroleum engineering, geothermal energy, offshore technology, energy geostructures, geomechanical numerical models and computational rail geotechnics.
High Performance Computing For Structural Mechanics And Earthquake Tsunami Engineering
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Author : Shinobu Yoshimura
language : en
Publisher: Springer
Release Date : 2015-10-26
High Performance Computing For Structural Mechanics And Earthquake Tsunami Engineering written by Shinobu Yoshimura and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-10-26 with Science categories.
Huge earthquakes and tsunamis have caused serious damage to important structures such as civil infrastructure elements, buildings and power plants around the globe. To quantitatively evaluate such damage processes and to design effective prevention and mitigation measures, the latest high-performance computational mechanics technologies, which include telascale to petascale computers, can offer powerful tools. The phenomena covered in this book include seismic wave propagation in the crust and soil, seismic response of infrastructure elements such as tunnels considering soil-structure interactions, seismic response of high-rise buildings, seismic response of nuclear power plants, tsunami run-up over coastal towns and tsunami inundation considering fluid-structure interactions. The book provides all necessary information for addressing these phenomena, ranging from the fundamentals of high-performance computing for finite element methods, key algorithms of accurate dynamic structural analysis, fluid flows with free surfaces, and fluid-structure interactions, to practical applications with detailed simulation results. The book will offer essential insights for researchers and engineers working in the field of computational seismic/tsunami engineering.
Lumped Macroelement Modeling Of Earth Retaining Structures Under Seismic Loading For Nonlinear Time History Analyses
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Author : Arastoo Dasmeh
language : en
Publisher:
Release Date : 2019
Lumped Macroelement Modeling Of Earth Retaining Structures Under Seismic Loading For Nonlinear Time History Analyses written by Arastoo Dasmeh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
This dissertation addresses various engineering problems involving the seismic re- sponse modeling of earth-retaining structures. These are namely, (i) lateral pas- sive seismic behavior of ordinary skew-angled bridge abutments, (ii) lateral pas- sive seismic behavior of high-speed rail transition abutments (with no skew), and finally (iii) active and passive seismic behavior of (cantilevered) earth-retaining walls. The approach adopted for each problems is the same, which is to devise a macroelement model with physics-based parameters (e.g., soil density, shear strength, wall height, etc.) that captures salient response features. These models are able to predict the lateral capacity of the retained soil and residual displace- ments with a modest computational effort--as compared to, for example, predic- tive simulations carried out with three-dimensional finite element models--, which renders them to be amenable for repeated nonlinear time-history analyses required for performance-based seismic assessment and design. The three aforementioned problems are briefly described below: I. Presence of skew-angled abutments complicates the seismic behavior of or- dinary bridges, primary driver of which is the passive lateral resistance of the engineered backfill behind the abutment. The eccentricity of the soil reaction ii relative to the bridge's center of stiffness or mass causes a skew bridge to rotate under seismic excitations, and a nonuniform soil pressure distribution develops behind the abutment backwall. A distributed nonlinear spring model is devised here to represent the lateral passive reaction of the backfill soil. To that end, a modification factor is devised so that Log-Spiral Hyperbolic (LSH) backbone curves -which had been developed in prior research and were validated for back- fills of straight abutment-can be used to generate the backbone curves of the said springs. This new modeling approach is verified against three-dimensional finite element model simulations and is validated with data from large-scale experiments conducted at Brigham Young University that had produced direct measurements of load-deformation backbone curves for several skew angles. In the final step, the validated modified-LSH model is used in parametric studies to devise a simple bilinear load-deformation relationship that is parameterized with respect to the backwall height, abutment skew angle, and the backfill soil properties. This sim- ple relationship is intended for routine use in the capacity-based seismic design and analysis of skew bridges. II. California's High-Speed Rail (HSR) System is slated to traverse nearly the entire length of the state, and thus it will be exposed seismic risks from almost every known major tectonic fault there. The present study deals with the seismic responses of bridge-abutment transition backfills (BATBs), which are essential components of HSR bridges. BATBs provide a gradual variation of vertical stiff- ness between the bridge deck and the engineered backfill zone, enabling smooth operations for trains traveling at high speeds. All prior investigations focused on this vertical stiffness in order to better characterize the localized vertical dif- ferential movements around BATBs under periodic high axial loads from train sets. Lateral behavior of BATBs, which are important under seismic loads, have not been previously investigated. The present study offers a parametric nonlin- ear lateral force-displacement backbone curve for BATBs that is verified against iii three-dimensional finite element models and validated against data from large- scale tests conducted at Brigham Young University. The parametric curve takes backwall height as well as abutment skew angle into account. III. Performance-based seismic assessment (PBSA) of earth retaining struc- tures requires the use of accurate yet computationally efficient analysis models. To date, limit equilibrium models offered the most computationally efficient re- sults, but they only produce estimates of peak lateral seismic forces and cannot be used in nonlinear time-history analyses. While detailed finite element models can possibly fill this need, they are not amenable for repeated simulations required for quantifying the uncertainties associated with estimated ground motions within the PBSA framework. A novel Lumped Impedance Model (LIM) is developed in this study that generates as accurate solutions as detailed FE models, with trivial computational effort. The model is able to also reproduce lateral passive load-deformation backbone curves as predicted by a state-of-the art limit equi- librium model, by its design. The computational saving offered by LIM is due to lumping of mass and stiffness of the retained soil, and the strategic placement of elastoplastic macroelements along pre-calculated active and passive failure hy- perplanes. LIM is verified against analytical solutions in frequency-domain for linear response regimes--wherein it is shown that LIM can accurately capture the frequency-dependent responses of the retained soil--as well as other previous studies for inelastic conditions. LIM is also verified against detailed FEM sim- ulations of cantilevered retaining wall subjected to both narrow- and broadband excitations, and it is shown that both elastic and inelastic responses of the retained soil (including residual wall displacements and rotations) are adequately captured. Finally, a framework for PBSA of earth-retaining structures using LIM as the pre- dictive model is proposed and its use is demonstrated through an example seismic assessment application wherein a fragility curve is computed. iv
The Nonlinear Three Dimensional Response Of Structures To Earthquake Excitation
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Author : Bruce Malcolm Mason
language : en
Publisher: 1978.
Release Date : 1978
The Nonlinear Three Dimensional Response Of Structures To Earthquake Excitation written by Bruce Malcolm Mason and has been published by 1978. this book supported file pdf, txt, epub, kindle and other format this book has been release on 1978 with Buildings categories.