NONLINEAR MODEL FOR SEISMIC ANALYSIS OF R/C FRAMED STRUCTURES

Abstract

The main objective of this thesis is the extrapolation of DRAIN-2D program used for nonlinear seismic analysis of RIC structures. The extrapolation of the program uses an advanced hysteretic model to represent the hysteretic behavior of the structural elements. The modified program is called SRA-2DS (Seismic Response Analysis of two-Dimensional Structures). The hysteretic model is the three-parameter model and it is used to model the flexural behavior of the RIC elements. It operates on a tri-linear primary curve and has the capabilities of representing splitting of steel reinforcement from the concrete, strength loss due to highly repetition of loading cycles, and stiffness loss due to crack propagation. The properties of the hysteretic model depend on the parameters a, (3& y. The values ofthese parameters depend on the physical properties of the structural components and on the intensity of the applied earthquake. Two different approaches are developed to address the values of these parameters.• The first approach depends on true/false statement evaluation of the structural components. The other is represented by a closed form expression (Analytical formulation). The results of using the developed approaches in earthquake analysis indicate that they can address the parameters a,(3, y precisely according to the comparison made with some experimental tests. Also, the results of the current version of SRA-2DS program are accurate to a satisfactory degree according to the comparison made with some experimental tests and the results obtained from DRAIN-2DX program. The other objectives of the thesis are the development of planer model for analysis of RIC space structures and inclusion of strain rate of loading in the stress-strain relation of steel and concrete.