A damage-based definition of effective peak acceleration

Biswajit Basu, Graduate Student, Vinay K. Gupta, Associate Professor ^*

Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India

Keywords

 ground motion process; effective peak acceleration; peak ground acceleration; expected cumulative damage; bilinear hysteretic oscillator; stochastic averaging

Abstract

This paper presents a rational basis for obtaining the Effective Peak Acceleration (EPA) of a given ground motion process. The proposed formulation considers the statistical variability in the ground motion, and is centred on the idea of explicitly linking EPA with expected cumulative damage in the structures due to the inelastic excursions. The structural behaviour has been modelled by a Single-Degree-Of-Freedom (SDOF) bilinear hysteretic oscillator. EPA is considered to be the expected PGA of a scaled ground motion process such that this oscillator undergoes a specified expected damage under the unscaled process if it is linearly designed for the scaled process. For estimation of the damage, the oscillator has been replaced by an equivalent linear oscillator through stochastic averaging. A parametric study has been carried out to investigate the dependence of EPA on several governing parameters, and it has been shown that despite the strong dependence of EPA on oscillator time period, it may be possible to obtain period-averaged EPA values for several ground motion processes for engineering applications.