Analysis of shaking table‐structure interaction effects during seismic simulation tests

Abstract

SUMMARYAn analytical model is developed to evaluate performance characteristics of unidirectional seismic simulators (shaking tables). The validity of the model is verified with experimental measurements of the frequency response of the shaking table at the Catholic University of Peru.Interaction effects between shaking table and structure are first studied by analysing the response of a two DOF (degree of freedom) oscillator with mechanical properties representative of the actuator-table-structure system. A single DOF viscoelastic oscillator representing the structural test specimen is then included in the analytical model of the seismic simulator, and the behaviour of the combined system is evaluated, in the frequency domain, in terms of response stability and accuracy of reproduction of the command signal. Numerical simulations of system response under different load conditions are subsequently performed in order to study the influence of shaking table and test structure characteristics on the interaction phenomenon.The results obtained explain some of the performance degradation observed in seismic simulation tests involving very heavy structures and provide guidelines for the design of more reliable shaking table systems.

Shake table real‐time hybrid simulation techniques for the performance evaluation of buildings with inter‐story isolation

“…Furthermore, shake tables are inherently nonlinear devices due to nonlinearities in actuator behavior, friction in the table, [21] and control-structure interaction (CSI). [22,23] Therefore, it is challenging to reproduce a desired acceleration over a wide range of frequencies. Recently, model-based acceleration tracking approaches have demonstrated excellent tracking of predefined accelerations considering shake table dynamics and, moreover, can be adapted to track accelerations calculated in real time (e.g., Kuehn et al [24] and Nakata [25] ).…”

“…Traditional shake table control strategies that require offline calculations (e.g., Fletcher, Simova and Mamucevski, Spencer and Yang) cannot be used for RTHS. Furthermore, shake tables are inherently nonlinear devices due to nonlinearities in actuator behavior, friction in the table, and control–structure interaction (CSI) . Therefore, it is challenging to reproduce a desired acceleration over a wide range of frequencies.…”

Real-time control of shake tables for nonlinear hysteretic systems

“…The natural frequency of the shake table system ω a (rad/s) is also known as oil column frequency, that is, f n,a (Hz) = ω a /2π = π -1 (βA 2 /Vm t ) 0.5 [5], in which A (in 2 ) is the actuator piston area; V (in 3 ) is the volume of oil in the actuator; and β (psi) is the bulk modulus of fluid.…”

“…In order to provide better understanding of the shake table system and to improve its performance, mathematical models were developed by many researchers such as Blondet and Esparza [3], Rinawi force may not be accurately known in advance. In these cases, real-time parameter estimators might be required for adaptive control schemes.…”

Analytical modelling of a large‐scale dynamic testing facility

“…Of those that have discussed the dynamics of seismic simulators, the number that has concentrated on the dynamics of uniaxial seismic simulators is relatively small (e.g. [2][3][4][5][6][7][8][9][10][11][12][13][14]). The likelihood that structural compliance in the test rig will affect performance has not often been considered.…”