The 14 th World Conference on Earthquake Engineering October 12-17, 2008, Beijing, China ANALYSIS OF SEISMIC RESPONSE OF FULLY GROUTED REINFORCED CONCRETE MASONRY SHEAR WALLS M. T. Shedid 1 , W. W. El-Dakhakhni 2 , and R. G. Drysdale 3 1 Ph.D. Candidate, Dept. of Civil Engineering, McMaster University, Hamilton. Ontario, Canada 2 Assistant Professor, Martini, Mascarin and George Chair in Masonry Design, Dept. of Civil Engineering, McMaster University, Hamilton. Ontario, Canada 3 Professor Emeritus, Dept. of Civil Engineering, McMaster University, Hamilton. Ontario, Canada Email: shedidmmt@mcmaster.ca , eldak@mcmaster.ca , drysdale@mcmaster.ca ABSTRACT : This paper presents detailed analyses of an experimental study conducted to evaluate the possibility of achieving high levels of ductility and energy dissipation in reinforced concrete masonry shear walls failing in flexure. The test program consisted of testing six reinforced concrete masonry shear walls to failure under reversed cyclic lateral loading. The current study focuses on documenting the levels of ductility attained by the walls, evaluating the contribution of flexure and shear deformations to the overall wall lateral displacement, and estimating the amount of energy dissipated by hysteretic damping. The measured and predicted wall capacities are discussed with respect to the MSJC code (2005) and the CSA S304.1 (2004). Analysis of the measured displacements showed that the shear displacement contribution of the test walls (all with height-to-length ratio of 2.0) to the overall wall displacement was significant but was not the same for all the walls. It was also shown that reinforced masonry shear walls can exhibit high levels of energy dissipation. KEYWORDS: Ductility, Energy dissipation, Shear Walls, Masonry 1. INTRODUCTION In regions where strong ground motions are anticipated, it is generally not economical to design shear wall buildings to remain elastic during a severe earthquake. Therefore, during a moderate to high seismic event, inelastic deformations are expected which result in a significant reduction in the walls’ seismic demand. For cantilever reinforced masonry shear walls, a ductile response can be achieved through the development of a flexural plastic hinge at the base of the wall which also results in a significant amount of energy dissipation (Drysdale and Hamid 2005). Currently, most seismic design methodologies rely on using prescriptive requirements that allow reduction in seismic design forces calculated based on elastic behavior to account for the effect of ductility in the structure. In the Masonry Standards Joint Committee code (MSJC 2005) in the United States and in the Euro-code (EC8), similar values for this ductility modification factor, DMF are assigned to reinforced concrete and reinforced masonry shear wall buildings. In the National Building Code of Canada (NBCC 2005), reinforced masonry shear wall construction is considered to be relatively brittle compared to reinforced concrete shear wall construction. The Canadian code assigns DMF values of 2.0 and 3.5 for moderately ductile masonry shear wall buildings and for ductile reinforced concrete shear wall buildings, respectively. Therefore, the reinforced concrete building is designed for 57% of the lateral load on the masonry building. The conservative Canadian values assigned to masonry shear wall structures may be mostly attributed to the poor performance of unreinforced masonry during past earthquakes (Priestly 1986). On the other hand, some studies indicated that a ductile response, which should reduce that demand by increasing the value of the DMF, is attainable. Englekirk and Hart (1982) proposed a displacement ductility of 1.5 and 3.0 for the serviceability limit state and the ultimate strength limit state, respectively, for reinforced masonry shear walls. Moreover, results of some research programs indicate that reinforced masonry shear walls, when properly proportioned, and constructed, provide reasonable ductility and adequate safety against seismic forces (Abrams 1986). The investigation presented herein indicates that, a displacement ductility of 3.0 can easily be attained with only minor degradation in wall capacity for high reinforcing ratios and much higher ductilities are possible for more moderate amounts of reinforcement.