Seismic simulation of RC wall-type structures

Reinforced concrete (RC) wall-type structures are crucial to the safety and serviceability of buildings subject to earthquakes. The shear strength of elements in walls depends strongly on the softening of concrete struts in the principal compression direction due to the principal tension in the perpendicular direction. By studying the shear behavior of isolated membrane elements, this softening phenomenon has been clarified for monotonic loading in the Softened Membrane Model (SMM) [Hsu TTC, Zhu RRH. Softened membrane model for reinforced concrete elements in shear. Struct J Amer Concrete Institute 2002; 99(4):460–9]. Recently, SMM was extended to cyclic loading, resulting in the Cyclic Softened Membrane Model (CSMM) [Mansour M, Hsu TTC. Behavior of reinforced concrete elements under cyclic shear: Part 1 — experiments. J Struct Eng, ASCE 2005; 131(1):44–53; Mansour M, Hsu TTC. Behavior of reinforced concrete elements under cyclic shear: Part 2–theoretical model. J Struct Eng, ASCE 2005;131(1):54–65]. In the present paper, the CSMM for elements is first formulated and then implemented in a finite element program, called Simulation of Concrete Structures (SCS), to predict the behavior of RC wall-type structures. SCS is based on the framework of OpenSees [Fenves GL. Annual workshop on open system for earthquake engineering simulation. Berkeley: Pacific Earthquake Engineering Research Center, UC; 2005]. The accuracy of the modeling technique is confirmed by comparing simulated responses with experimental data on nine framed shear walls reported by [Gao XD. Framed shear walls under cyclic loading. Ph.D. dissertation. Houston (TX): Department of Civil and Environmental Engineering, University of Houston; 1999]. This new modeling technique gives engineers greatly improved simulation capabilities.