טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKhaldoun Qadi
SubjectSeismic Non-Linear Response of Single Degree of Freedom
Systems Approximate Methods
DepartmentDepartment of Civil and Environmental Engineering
Supervisors Professor Levy Robert
Professor Emeritus Rutenberg Avigdor


Abstract

The purpose of the present study is to assess the accuracy of the various available approximation methods for defining an equivalent linear system to a simple nonlinear system subjected to earthquake excitations, and to suggest improved methods as appropriate.This study examined the earthquake response of non-linear systems. A simple model is used to describe several different single-degree-of-freedom systems. A numerical investigation of the response of these systems is performed using several earthquake records. The response is studied at various natural vibration periods, and values of damping ratio. The numerical results are presented as normalized response spectra with respect to the exact response values.

An approximate analytical method and a curve-fitting method for obtaining the earthquake response of a nonlinear system from an equivalent linear system are presented. The first method is an equivalent linearization technique, and the second extends and develops the curve fitting method of the so-called R-µ-T method introduced by Krawinkler and Nassar.

The new equivalent linearization method is compared to existing methods. From the comparisons, it is concluded that the proposed equivalent linearization method represents a significant improvement over currently available methods for predicting the earthquake response of nonlinear systems.

The R-µ-T method is performed in order to derive nonlinear response spectra for various groups of earthquake records. These records are selected so that each group represents the seismic properties of different regions. Also, in this work a design tables containing curve- fitting values for each region are presented, which can be used in design codes for obtaining the inelastic response of structures. A designer can predict the response of his building, without the need of investigating the nature of the nonlinear response of the structure.