An improved equivalent linear model of seismic isolation system with bilinear behavior

2014 ◽  
Vol 61 ◽  
pp. 113-126 ◽  
Author(s):  
Tao Liu ◽  
Tobia Zordan ◽  
Bruno Briseghella ◽  
Qilin Zhang
Keyword(s):  
Linear Model ◽  
Seismic Isolation ◽  
Isolation System ◽  
Equivalent Linear ◽  
Equivalent Linear Model

scholarly journals Evaluating the Accuracy of an Equivalent Linear Model in Predicting Peak Displacement of Seismic Isolation Systems using Single Friction Pendulum Bearings

2021 ◽  
Author(s):  
Thanh-Truc Nguyen ◽  
Nhan Dinh Dao
Keyword(s):  
Linear Model ◽  
Seismic Isolation ◽  
Peak Displacement ◽  
Equivalent Linear ◽  
Linear And Nonlinear ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Friction Pendulum ◽  
Equivalent Linear Model ◽  
Motion Types

This study evaluates the accuracy of an equivalent linear model in predicting peak nonlinear time-history displacement of seismic isolation systems with single friction pendulum bearings. To perform this evaluation, dynamic response of numerical models of 120 isolation systems subjected to 390 strong earthquake ground motions, including motions with pulse and motions without pulse, was analyzed and statistically processed. The results show that the equivalent linear model can partly predict the peak displacement of its counterpart nonlinear model. However, the equivalent model can also underestimate or overestimate the peak displacement. On average sense, the equivalent linear model underestimates small peak displacement and overestimates large peak displacement. It is also observed that the relationship between linear and nonlinear peak displacements depends on ground motion types. Based on the analysis data, equations representing relationship between linear and nonlinear peak displacements at different reliable levels for different ground motion types were proposed. These equations can be used in practice.

A Refined Model for Base-Isolated Bridges with Bi-Linear Hysteretic Bearings

1996 ◽  
Vol 12 (2) ◽  
pp. 245-273 ◽  
Author(s):  
J. S. Hwang ◽  
J. M. Chiou ◽  
L. H. Sheng ◽  
J. H. Gates
Keyword(s):  
Linear Model ◽  
Seismic Analysis ◽  
Elastic Stiffness ◽  
Elastic Displacement ◽  
Earthquake Ground Motion ◽  
Displacement Spectra ◽  
Equivalent Linear ◽  
Proposed Model ◽  
Isolated Bridges ◽  
Equivalent Linear Model

Recognizing that the inelastic displacement spectra with constant ductility ratios of an earthquake ground motion can be approximated by the equivalent elastic displacement spectra with the consideration of appropriate effective period shifts (or effective stiffness) and equivalent damping ratios, a refined equivalent linear model for the seismic analysis of base-isolated bridges with bi-linear hysteretic bearings is established in this paper using a system identification method. The parameters necessary to completely define a bi-linear hysteresis loop such as the elastic stiffness, yielding force, strain harden ratio and ductility ratio are all considered in the modeling. Eighteen California, one Washington and one Japan earthquake ground motions are used for the identification. The equivalent linear model established through the identification process is characterized as a modification of the current equivalent linear model provided by the AASHTO isolation guide specifications. Numerical comparisons indicate that the proposed model in general can predict accurately compared against the inelastic solutions and, therefore, the proposed model can be applied to the practical analysis of base-isolated bridges.

scholarly journals Effects of Strain Level and Number of Cycles of Seismic Motions on Equivalent Linear Model.

2002 ◽  
pp. 197-209 ◽  
Author(s):  
Yoshio SOEDA ◽  
Hideki TAMAI ◽  
Masahiro TANAKA ◽  
Koichiro TAKEZAWA ◽  
Futoshi MAEGAWA
Keyword(s):  
Linear Model ◽  
Strain Level ◽  
Equivalent Linear ◽  
Number Of Cycles ◽  
Equivalent Linear Model

Equivalent Linear Model for Existing Soil-Structure Systems

2016 ◽  
Vol 16 (02) ◽  
pp. 1450099 ◽  
Author(s):  
Amir Rezaei Sameti ◽  
Mohammad Ali Ghannad
Keyword(s):  
Linear Model ◽  
Soil Structure ◽  
Equivalent Linearization ◽  
Structure System ◽  
Super Structure ◽  
Sdof System ◽  
Equivalent Linear ◽  
Cone Model ◽  
Wide Range ◽  
Equivalent Linear Model

The concept of equivalent linearization is extended for the soil-structure systems, in which the strength ratio (defined as the ratio of the yielding strength to the elastic strength demand) is known rather than the ductility ratio. The nonlinear soil-structure system is replaced by a linear single-degree-of-freedom (SDOF) system, which can capture the response of the actual system with sufficient accuracy. The dynamic characteristics of the equivalent linear SDOF system are determined through a statistical approach. The super-structure is modeled by an inelastic SDOF system with bilinear behavior, and the homogeneous half space beneath the structure by a discrete model, following the Cone Model. To cover a wide range of soil-structure systems, a comprehensive parametric study is conducted using a set of nondimensional parameters for the soil-structure system. The accuracy of the equivalent linear parameters is then assessed. The results confirm that the proposed equivalent linear model can capture the simultaneous effects of soil-structure interaction (SSI) and nonlinearity in the super-structure concerning the maximum inelastic response of the soil-structure system.

scholarly journals Seismic Soil-Structure Interaction Analysis of Isolated Nuclear Power Plants in Frequency Domain

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Zhiguang Zhou ◽  
Xiaodong Wei
Keyword(s):  
Soil Profile ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Interaction Analysis ◽  
Isolation System ◽  
Vertical Excitation ◽  
Structure Response ◽  
Equivalent Linear

One important aspect of applying seismic isolation to Nuclear Power Plants (NPPs) is that the complex interactions of flexible soil, flexible isolators, and stiff structures require careful investigation. In this paper, a NPP model was used to investigate the effects of SSI and the effects of changing soil and isolator properties on seismic response of an isolated NPP. The following aspects are considered in the study: horizontal excitation and vertical excitation; linear and equivalent-linear models of the isolators; scaling of the shear modulus of the soil profile model; and scaling of the horizontal equivalent stiffness of the isolators. It was found that Pseudospectral Acceleration (PSA) in the nuclear structure at the frequencies near the natural frequency of the structure increase with elevation, and the difference between the in-structure response spectral acceleration with and without SSI effects is concentrated at the frequencies near the natural frequencies of the superstructure. It is also found that the linear SSI analysis underestimates the in-structure response of the nuclear structures compared to the equivalent-linear SSI analyses, and the soil profile properties directly affect the effectiveness of the isolation system.

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