scholarly journals Accuracy of Analytical Models to Predict Primary and Secondary System Response in Seismically Isolated Buildings

2021 ◽  
Author(s):  
Cengiz Ipek ◽  
Eric D. Wolff ◽  
Michael C. Constantinou
Keyword(s):  
Seismic Isolation ◽  
Response Spectra ◽  
Analytical Models ◽  
System Response ◽  
Primary System ◽  
Secondary System ◽  
Viscous Dampers ◽  
Floor Response Spectra ◽  
Analytical Results ◽  
Seismically Isolated

Abstract Seismic isolation is generally considered an effective earthquake protection strategy. As application of seismic isolation increases, decisions on the use of one particular isolator versus another isolator increasingly depend on computed responses with complex analytical models. Accordingly, validation of analytical models to predict primary (structural) and secondary system (non-structural component) response in seismically isolated buildings becomes very important. This paper presents comparisons of experimental and analytical results on the primary and secondary system response of a building model in order to provide information on the accuracy of the predicted response. The tested model was configured as a 6-story building at quarter length scale in a moment-frame configuration, and with the following seismic isolation systems: a) Low damping elastomeric bearings with and without linear or nonlinear viscous dampers, b) Single Friction Pendulum (FP) bearings with and without linear or nonlinear viscous dampers, and c) Lead-rubber bearings. Response quantities compared include story drifts and isolator shear forces and displacements for the primary system, and peak floor total velocities and floor response spectra that relate to secondary system response. This paper presents samples results out of a total of 288 comparisons of experimental and analytical results presented in an MCEER report. It is shown that the primary and secondary system response is computed with sufficient accuracy by the analytical models but some response quantities may be underestimated or overestimated by significant amounts.

scholarly journals Fragility Assessments of Multi-Story Piping Systems within a Seismically Isolated Low-Rise Building

2018 ◽  
Vol 10 (10) ◽  
pp. 3775 ◽  
Author(s):  
Yonghee Ryu ◽  
Shinyoung Kwag ◽  
Bu‐Seog Ju
Keyword(s):  
Seismic Isolation ◽  
Ground Motions ◽  
Seismic Energy ◽  
Analytical Models ◽  
Piping System ◽  
Building Structure ◽  
Strong Ground Motions ◽  
Piping Systems ◽  
Seismically Isolated ◽  
Strong Ground

A successful, advanced safety design method for building and piping structures is related to its functionality and sustainability in beyond-design-basis events such as extremely strong ground motions. This study develops analytical models of seismically isolated building-piping systems in which multi-story piping systems are installed in non-isolated and base-isolated, low-rise buildings. To achieve the sustainable design of a multi-story piping system subjected to strong ground motions, Triple Friction Pendulum (TFP) elements, specifically TFP bearings, were incorporated into the latter building structure. Then, a seismic fragility analysis was performed in consideration of the uncertainty of the seismic ground motions, and the piping fragilities for the seismically non-isolated and the base-isolated building models were quantified. Here, the failure probability of the piping system in the non-isolated building was greater than that in the seismically isolated building. The seismic isolation design of the building improved the sustainability and functionality of the piping system by significantly reducing the seismic energy of extreme ground motions which was input to the building structure itself.

scholarly journals Analysis of Seismic Soil-Structure Interaction for a Nuclear Power Plant (HTR-10)

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaoxin Wang ◽  
Qin Zhou ◽  
Kaixin Zhu ◽  
Li Shi ◽  
Xiaotian Li ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Soil Structure ◽  
Power Plants ◽  
Response Spectra ◽  
Seismic Excitation ◽  
Primary System ◽  
Fe Model ◽  
Floor Response Spectra ◽  
Fixed Base ◽  
Test Reactor

The response of nuclear power plants (NPPs) to seismic events is affected by soil-structure interactions (SSI). In the present paper, a finite element (FE) model with transmitting boundaries is used to analyse the SSI effect on the response of NPP buildings subjected to vertically incident seismic excitation. Analysis parameters that affect the accuracy of the calculations, including the dimension of the domain and artificial boundary types, are investigated through a set of models. A numerical SSI analysis for the 10 MW High Temperature Gas Cooled Test Reactor (HTR-10) under seismic excitation was carried out using the developed model. The floor response spectra (FRS) produced by the SSI analysis are compared with a fixed-base model to investigate the SSI effect on the dynamic response of the reactor building. The results show that the FRS at foundation level are reduced and those at higher floor levels are altered significantly when taking SSI into account. The peak frequencies of the FRS are reduced due to the SSI, whereas the acceleration at high floor levels is increased at a certain frequency range. The seismic response of the primary system components, however, is reduced by the analysed SSI for the HTR-10 on the current soil site.

Spectral Analysis of Complex Systems Supported at Several Elevations

1976 ◽  
Vol 98 (2) ◽  
pp. 162-165 ◽  
Author(s):  
H. J. Thailer
Keyword(s):  
Spectral Analysis ◽  
Complex Systems ◽  
Response Spectra ◽  
System Response ◽  
Theoretical Justification ◽  
Spectral Analyses ◽  
Floor Response Spectra ◽  
Discrete Mass

This paper presents the theoretical justification for a method for computing realistic system response from seismic spectral analyses. The method is applicable to complex discrete mass systems which are supported at several locations within a structure and at which different floor response spectra are defined.

Stochastic Floor Response Spectra for an Actively-Controlled Secondary System

2011 ◽  
Author(s):  
Takashi Mochio
Keyword(s):  
Structural Response ◽  
Response Spectra ◽  
Value Theory ◽  
Secondary System ◽  
Linear Quadratic ◽  
Gaussian Random Process ◽  
Floor Response Spectra ◽  
Active Mass Damper ◽  
State Space System ◽  
Response Amplification

The purpose of this paper is to propose a newly floor response spectra (FRS) in order to evaluate simply the structural response of the actively-controlled secondary system subjected to earthquake. This paper adopts a linear single-degree-of-freedom system as a main structure and an active mass damper (AMD) system as the active control technology. Also, the earthquake wave is modeled as product of a non-stationary envelope function and a stationary Gaussian random process of which power spectral density is equal to the Kanai-Tajimi spectrum. The control design is executed by using linear quadratic Gaussian control strategy against an enlarged state space system. Finally, the response amplification factor is given by the combination of the obtained statistical response values and the extreme value theory. Analytical results are compared with numerical simulations, and both show a good agreement. As a result, it seems that the validity of the proposed technique is confirmed.

Shaking Table Tests With Large Test Specimens of Seismically Isolated FBR Plants: Part 3—Ultimate Behavior of Upper Structure and Rubber Bearings

2009 ◽  
Author(s):  
Shuichi Yabana ◽  
Kenji Kanazawa ◽  
Seiji Nagata ◽  
Seiji Kitamura ◽  
Takeshi Sano
Keyword(s):  
Seismic Isolation ◽  
Response Spectra ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Nuclear Facilities ◽  
Restoring Force ◽  
Isolation System ◽  
Seismically Isolated ◽  
Design Earthquake ◽  
Rubber Bearings

This paper describes results of shaking table tests to grasp ultimate behavior of seismic isolation system under extremely strong earthquake motions, including failure of rubber bearings. The results of the shaking table tests are expected to be useful for the design of seismically isolated nuclear facilities, especially fast breeder reactor (FBR) plants. In the test, lead rubber bearings, of which the diameter is 505 mm and about 1/3 scale of a prototype in planning FBR plants, are used; the test specimens are loaded by the largest three-dimensional shaking table in E-defense of National Research Institute for Earth Science and Disaster Prevention (NIED) of Japan. Failure of rubber bearings occurs with amplified tentative design earthquake motions. From the tests, the ultimate responses of the upper structure and rubber bearings are presented. In particular, the change of floor response spectra and restoring force characteristics of rubber bearings according to increase of input motions is discussed. Furthermore, mechanism of the failure of rubber bearings is investigated from the observation of failure surfaces and cut sections, static loading tests, and material tests of rubber bearings. Finally, the function of seismic isolation system after the failure of a part of rubber bearings is confirmed under the tentative design earthquake.

scholarly journals Evaluation of Clearance to Stop Requirements in A Seismically Isolated Nuclear Power Plant

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6156
Author(s):  
Gyeonghee An ◽  
Minkyu Kim ◽  
Jae-Wook Jung ◽  
Gilberto Mosqueda ◽  
Joaquin Fabian Marquez
Keyword(s):  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Structural Model ◽  
Large Strain ◽  
Performance Criteria ◽  
Analytical Models ◽  
Design Standards ◽  
Strain Behavior ◽  
Seismically Isolated

Seismically isolated nuclear power plants (NPPs) can provide substantial benefits towards reducing the failure probability of NPPs, especially for beyond design basis earthquake shaking. One risk posed by seismic isolation is the potential for pounding to a stop or moat wall, with currently little guidance provided by design standards on how to address this concern. In this paper, a structural model of an isolated NPP based on the Advanced Power Reactor 1400 MW is enveloped with moat walls and advanced bearing models. The bearing models account for large strain behavior through failure based on full-scale experiments with lead rubber bearings (LRBs). Using these analytical models and a measured ultimate property diagram from LRB failure tests, the range of clearance to the stop considering the performance criteria for the NPP is investigated. Although the analysis results are dependent on the particular models, ground motions, and criteria employed, this research provides an overview of the seismic response and performance criteria of an isolated NPP considering the clearance to the stop.

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