Collapse capacity of soil‐structure systems under pulse‐like earthquakes

Summary In this paper, a comprehensive study is carried out to examine the possibility of dynamic instability produced in soil-structure systems using an ensemble of 50 pulse-like records. A number of structural models with various vibration periods varying from 0.1 to 2 s are used in this study. The superstructure is simulated as a non-linear SDOF oscillator with a two-segment backbone curve having negative post-yield stiffness. The soil is idealized based on the cone model concept widely used for practical purposes. The results of this investigation demonstrate that as the pulse period increases, the collapse relative lateral strength ratio decreases and probability of dynamic instability enhances. Moreover, soil flexibility makes the system dynamically more unstable, and as the non-dimensional frequency increases, the collapse relative lateral strength ratio highly reduces. Additionally, the aspect ratio has insignificant effects on the collapse relative lateral strength ratio. Furthermore, comparison of the collapse relative lateral strength ratios resulting from pulse-like motions with those obtained from studies under non-pulse-like motions (Miranda and Akkar; FEMA 440) for fixed-base conditions shows that high-velocity pulses exacerbate the dynamic instability problem and decrease the collapse relative lateral strength ratio. Copyright © 2014 John Wiley & Sons, Ltd.