The impact of a PEER funded research project "Implementation of Frequency-Dependent Impedance Functions in OpenSees" is highlighted below. The project Principal Investigator (PI) is Jian Zhang, Professor of Civil & Environmental Engineering, UCLA. The Research Team includes S. Farid Ghahari, Project Scientist, UCLA and Ertugrul Taciroglu, Professor and Chair of Civil & Environmental Engineering, UCLA (Senior Collaborator).
The dynamic nonlinear time-history analysis plays a critical role in PEER Performance-Based Engineering (PBE). While nonlinear behavior of the structures can be modeled with relatively good accuracy, the soil-foundation subsystem is still highly uncertain. One of the sources of the uncertainties is the frequency-dependent behavior of the soil-foundation impedance function. Current FE modeling softwares are not capable of including frequency-dependency in the time domain unless IF is modeled through physical lumped parameter models.
However, there is no unique and general way to develop such lumped models for any IF. Also, there is no solution to guarantee the stability of the entire system. This project will provide engineers and researchers with an extended version of the OpenSees by which they can carry out more accurate nonlinear time-history analysis while frequency-dependent soil-structure interaction effects are taken into account.