The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Rafael Riddell - One of the best experts on this subject based on the ideXlab platform.
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Inelastic Response spectrum early history
Earthquake Engineering & Structural Dynamics, 2008Co-Authors: Rafael RiddellAbstract:Detailing the time period from, roughly, 1950 through 1980, this Historical Note documents the development of the initial concept of the Inelastic Response spectrum and how it evolved to become the basis for rational procedures for earthquake-resistant design, which are used even today. Copyright © 2008 John Wiley & Sons, Ltd.
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Inelastic Response of one storey asymmetric plan systems subjected to bi directional earthquake motions
Earthquake Engineering & Structural Dynamics, 1999Co-Authors: Rafael Riddell, Hernan SantamariaAbstract:The Inelastic Response of one-storey systems with one axis of asymmetry subjected to bi-directional base motion is studied in this paper. The effect of the system parameters on Response is also evaluated: uncoupled torsional-to-lateral frequency ratio, stiffness eccentricity, and yield strength of the lateral resisting elements. The ensemble of earthquake records used consists of 15 two-component strong ground motions. The Response to uni-directional excitation is considered first to examine the influence of the system parameters and to serve as a basis to examine the results of the bi-directional case, which are presented in terms of average spectra for bi- over uni-directional lateral-deformation ratios. It is shown that the effect of Inelastic behaviour is, on the average, noteworthy for stiff structures, in turn, the same structures are the most affected by the action of bi-directional ground motions. The effect of the relative intensity of the two orthogonal ground motion components is also studied. Copyright © 1999 John Wiley & Sons, Ltd.
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Inelastic Response of one‐storey asymmetric‐plan systems subjected to bi‐directional earthquake motions
Earthquake Engineering & Structural Dynamics, 1999Co-Authors: Rafael Riddell, Hernan Santa-mariaAbstract:The Inelastic Response of one-storey systems with one axis of asymmetry subjected to bi-directional base motion is studied in this paper. The effect of the system parameters on Response is also evaluated: uncoupled torsional-to-lateral frequency ratio, stiffness eccentricity, and yield strength of the lateral resisting elements. The ensemble of earthquake records used consists of 15 two-component strong ground motions. The Response to uni-directional excitation is considered first to examine the influence of the system parameters and to serve as a basis to examine the results of the bi-directional case, which are presented in terms of average spectra for bi- over uni-directional lateral-deformation ratios. It is shown that the effect of Inelastic behaviour is, on the average, noteworthy for stiff structures, in turn, the same structures are the most affected by the action of bi-directional ground motions. The effect of the relative intensity of the two orthogonal ground motion components is also studied. Copyright © 1999 John Wiley & Sons, Ltd.
George Gazetas - One of the best experts on this subject based on the ideXlab platform.
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phenomenological model applied to Inelastic Response of soil pile interaction systems
Soils and Foundations, 2005Co-Authors: Nikos Gerolymos, George GazetasAbstract:ABSTRACT A dynamic nonlinear Winkler spring model, is developed for the seismic Response of deep foundations. The model utilizes the phenomenological “BWGG” model (outlined in a companion paper), and it can treat the Inelastic Response of both the soil and the pile. The nonlinear reaction of the soil is modeled realistically by the BWGG interaction springs and dashpots, with due consideration to effects such as : separation (gapping) of the pile or caisson from the soil, radiation damping, and loss of strength due to pore-water pressure development. The modeling of pile Inelasticity is also versatile, and can treat from well-reinforced to poorly-reinforced concrete sections. The necessity for the proposed model arises from the difficulty to predict the large-amplitude dynamic Response of piles up to failure. The BWGG-Winkler model is validated through the results of in-situ monotonic and dynamic pile load tests. It is further utilized to study the nonlinear soil-pile interaction under lateral monotonic loading. The results of the model are compared with the venerable Broms (1964) theory for pile lateral capacity
Masaki Shiratori - One of the best experts on this subject based on the ideXlab platform.
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A JSME Code Case on Piping Seismic Design Based on Inelastic Response Analysis and Strain-Based Fatigue Criteria
Journal of Pressure Vessel Technology-transactions of The Asme, 2020Co-Authors: Masaki Morishita, Akihito Otani, Tomoyoshi Watakabe, Izumi Nakamura, Tadahiro Shibutani, Masaki ShiratoriAbstract:Abstract A Code Case in the framework of the Nuclear Codes and Standards of Japan Society of Mechanical Engineers (JSME) has been published to incorporate seismic design evaluation methodologies for piping systems by detailed Inelastic Response analysis and strain-based fatigue criteria as an alternative design rule to the current rule, in order to provide a more rational seismic design evaluation by taking directly the Response reduction due to plasticity energy absorption into account. The Code Case provides two strain-based criteria: one is a limit to maximum amplitude of equivalent strain amplitude derived from detailed analysis and the other is a limit to the fatigue usage factor also based on the equivalent strain amplitude. Some discussions are provided on the adequacy of additional damping in the simplified Inelastic analysis and the safety margin and reliability of fatigue evaluation by the detailed Inelastic Response analysis provided in the Code Case.
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Seismic Qualification of Piping Systems by Detailed Inelastic Response Analysis: Part 1 — A Code Case for Piping Seismic Evaluation Based on Detailed Inelastic Response Analysis
Volume 8: Seismic Engineering, 2017Co-Authors: Masaki Morishita, Akihito Otani, Tomoyoshi Watakabe, Izumi Nakamura, Tadahiro Shibutani, Masaki ShiratoriAbstract:A Code Case in the framework of the Nuclear Codes and Standards of Japan Society of Mechanical Engineers (JSME) is currently under development to incorporate seismic design evaluation methodologies for piping systems by detailed Inelastic Response analysis and strain-based fatigue criteria as an alternative design rule to the current rule, in order to provide a more rational seismic design evaluation by taking directly the Response reduction due to plasticity energy absorption into account. The Code Case provides two strain-based criteria; one is a limit to maximum amplitude of equivalent strain amplitude derived from detailed analysis and the other is a limit to the fatigue usage factor also based on the equivalent strain amplitude. The Code Case also provides an evaluation method by simplified Inelastic analysis with an additional damping taking the Response reduction due to plasticity into account. Some discussions are provided on the adequacy of additional damping in the simplified Inelastic analysis and the safety margin and reliability of fatigue evaluation by the detailed Inelastic Response analysis provided in the Code Case.
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Seismic Qualification of Piping System by Detailed Inelastic Response Analysis: Part 2 — A Guideline for Piping Seismic Inelastic Response Analysis
Volume 8: Seismic Engineering, 2017Co-Authors: Akihito Otani, Masaki Morishita, Tomoyoshi Watakabe, Izumi Nakamura, Tadahiro Shibutani, Masaki ShiratoriAbstract:A Code Case in the framework of JSME Nuclear Codes and Standards is currently being developed to incorporate seismic design evaluation of piping by detailed elastic-plastic Response analysis and strain-based fatigue criteria as an alternative design rule to the current rule, in order to provide a more rational seismic design evaluation. The Code Case provides two strain-based criteria; one is a limit to maximum amplitude of equivalent strain amplitude derived from detailed analysis and the other is a limit to the fatigue usage factor also based on the equivalent strain amplitude. A guideline for piping seismic analysis based on Inelastic Response analysis is also being developed as a mandatory appendix for the code case. The guideline provides the methodology to obtain the elastic and plastic strains in seismic Response and contains descriptions for analysis code, FE modeling including material property definition, time history analysis method, damping, seismic input condition and verification and validation method. This paper introduces the outlines of them.
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Seismic Qualification of Piping Systems by Detailed Inelastic Response Analysis: Part 4 — Second Round Benchmark Analyses With Stainless Steel Piping Component Test
Volume 8: Seismic Engineering, 2017Co-Authors: Tomoyoshi Watakabe, Masaki Morishita, Akihito Otani, Izumi Nakamura, Tadahiro Shibutani, Masaki ShiratoriAbstract:Some studies concerning ultimate strength of piping under seismic loads concluded that there is a large design margin until failure, even if the stress calculated based on the current design method does not satisfy design criteria. To provide a more rational seismic design, a new Code Case for seismic design of piping is now under development in the framework of JSME Nuclear Codes and Standards. The Code Case incorporates a dynamic elastic-plastic analysis procedure by employing finite element analysis as an alternative to the current design analysis method of elastic assumption. To confirm the applicability of Inelastic Response analysis, benchmark analyses have been conducted. In the first round benchmark, a carbon steel elbow analysis was performed. In this report, a second round benchmark with a stainless steel elbow and tee is introduced. The second benchmark aims to establish an analysis procedure for stainless steel piping and tee piping of complicated shapes. The second benchmark results provided a practical analysis method for stainless steel piping, and the Code Case was expanded so that it could be applied not only to carbon steel piping but also to stainless steel piping. The second benchmark also challenged analyses of a tee having complicated geometry. These results provide some important knowledge, and they will be included in the Code Case.
A R Srinivasa - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of the Inelastic Response of pig and rat skin under uniaxial cyclic mechanical loading
Experimental Mechanics, 2020Co-Authors: N Afsarkazerooni, A R Srinivasa, J C CriscioneAbstract:Skin is a highly non-linear, anisotropic, rate dependent Inelastic, and nearly incompressible material which exhibits substantial hysteresis even under very slow (quasistatic) loading conditions. In this paper, a series of uniaxial cyclic loading tests of porcine and rat skin at different strain rates and with samples oriented in different directions (with respect to the spine) were conducted to study the effect of strain rate and samples orientations with respect to spine on Mullins-type softening and skin Inelastic Response. A noteworthy feature of skin is that, similar to certain filled rubbers, its mechanical Response shifts after the first extension and exhibits softening and hysteresis when loaded under cyclic tension and Mullins-type softening is observed. The results of these strain-controlled cyclic loading tests also indicated that the extent of softening is different for different strain rates and orientations. Also, a substantial hysteresis persists even at very low strain rates indicating Inelastic behavior beyond the rate sensitive viscoelastic Response. Through this series of experiments, by investigating the effect of strain rate on pig skin and rat skin, we conclude that the skin Response is rate dependent but Inelastic and shows irreversible changes in fiber orientation which are observed in histology results. Also, skin shows persistent deformation that is only partially recovered even after a long period of unloading.
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Inelastic Response of solids described by implicit constitutive relations with nonlinear small strain elastic Response
International Journal of Plasticity, 2015Co-Authors: K R Rajagopal, A R SrinivasaAbstract:Abstract We develop a model to describe the Inelastic Response of bodies that exhibit non-linear Response even in the small strain regime. We introduce a new approach to modeling the Inelastic Response of materials by gainfully exploiting the discontinuity of the functions that appear in the constitutive relations to describe a plethora of Inelastic Responses that have been observed. The model that has been developed and its generalizations can be used to describe the Response of geomaterials such as clay and rocks, traditional materials such as Aluminum and several polymeric solids, as well as modern intermetallic alloys.
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mechanics of the Inelastic behavior of materials part ii Inelastic Response
International Journal of Plasticity, 1998Co-Authors: K R Rajagopal, A R SrinivasaAbstract:Abstract This is the second of a two part paper dealing with the Inelastic Response of materials. Part I (see Rajagopal and Srinivasa, 1998 International Journal of Plasticity 14 , 945–967) dealt with the structure of the constitutive equations for the elastic Response of a material with multiple natural configurations. We now focus attention on the evolution of the natural configurations. We introduce two functions-the Helmholtz potential and the rate of dissipation function—representing the rate of conversion of mechanical work into heat. Motivated by, and generalizing the work of Ziegler (1963) in Progress in Solid Mechanics , Vol. 4, North-Holland, Amsterdam/New York; (1983) An Introduction to Thermodynamics, North-Holland, Amsterdam/New York) we then assume that the evolution of the natural configurations occurs in such a way that the rate of dissipation is maximized. This maximization is subject to the constraint that the rate of dissipation is equal to the difference between the rate of mechanical working and the rate of increase of the Helmholtz potential per unit volume. This then allows us to derive the constitutive equations for the stress Response and the evolution of the natural configurations from these two scalar functions. Of course, the maximum rate of dissipation criterion that is stated here is only an assumption that holds for a certain class of materials under consideration. Our quest is to see whether such an assumption gives reasonable results. In the process, we hope to gain insight into the nature of such materials. We demonstrate that the resulting constitutive equations allow for Response with and without yielding behavior and obtain a generalization of the normality and convexity conditions. We also show that, in the limit of quasistatic deformations, if one considers materials that possess yielding behavior, then the constitutive equations reduce to those corresponding to the strain space formulation of the rate independent theory of plasticity (see e.g. Naghdi (1990) Journal of Applied Mathematics and Physics A345 , 425–458.). Moreover, in this limit, the maximum rate of dissipation criterion, as stated here, is equivalent to the work inequality of Naghdi and Trapp (1975) Quartely Journal of Mechanics and Applied Mathematics 28 , 25–46). The main results together with an illustrative example are presented.
Nikos Gerolymos - One of the best experts on this subject based on the ideXlab platform.
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phenomenological model applied to Inelastic Response of soil pile interaction systems
Soils and Foundations, 2005Co-Authors: Nikos Gerolymos, George GazetasAbstract:ABSTRACT A dynamic nonlinear Winkler spring model, is developed for the seismic Response of deep foundations. The model utilizes the phenomenological “BWGG” model (outlined in a companion paper), and it can treat the Inelastic Response of both the soil and the pile. The nonlinear reaction of the soil is modeled realistically by the BWGG interaction springs and dashpots, with due consideration to effects such as : separation (gapping) of the pile or caisson from the soil, radiation damping, and loss of strength due to pore-water pressure development. The modeling of pile Inelasticity is also versatile, and can treat from well-reinforced to poorly-reinforced concrete sections. The necessity for the proposed model arises from the difficulty to predict the large-amplitude dynamic Response of piles up to failure. The BWGG-Winkler model is validated through the results of in-situ monotonic and dynamic pile load tests. It is further utilized to study the nonlinear soil-pile interaction under lateral monotonic loading. The results of the model are compared with the venerable Broms (1964) theory for pile lateral capacity