ARTICLE IN PRESS Engineering Structures ( ) – Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct Behavior of fully grouted reinforced concrete masonry shear walls failing in flexure: Analysis Marwan T. Shedid ∗,1 , Wael W. El-Dakhakhni 2 , Robert G. Drysdale 3 Department of Civil Engineering, McMaster University, Hamilton, Ontario, Canada article info Article history: Received 3 October 2008 Received in revised form 6 March 2009 Accepted 9 March 2009 Available online xxxx Keywords: Concrete masonry Cyclic loads Damping Ductility Energy dissipation Shear deformation Stiffness Walls abstract This paper contains analysis details of an experimental study conducted to evaluate the ductility and energy dissipation characteristics of reinforced concrete masonry shear walls failing in flexure. The test program consisted of six reinforced concrete masonry shear walls tested under reversed cyclic lateral displacements simulating seismic loading effects. This paper focuses on documenting the levels of ductility attained by the walls and evaluating the contribution of flexure and shear deformations to the overall wall lateral displacement. Analysis of the measured displacements showed that the contribution of shear displacement to the overall wall displacement was significant (up to 28% of total displacement at maximum load) but was not the same for all the walls having height-to-length ratio of 2.0. Displacement ductility values up to 4.5 and 11.4 were measured corresponding to maximum load and 20% strength degradation, respectively. Values up to 3.5 were calculated for the ductility-related seismic response modification factor for the test walls corresponding to design drift levels of 1%. The relationship between the energy dissipation and the ratio of the post-yield to the yield displacement was found to be almost linear for the test walls. In addition, the wall stiffnesses degrade rapidly to about 50% of their initial stiffness at very low drift levels (0.1% drift); however, the test walls maintained at least 80% of their maximum strength up to large displacements (2.2% drift). © 2009 Elsevier Ltd. All rights reserved. 1. Introduction In regions where strong ground motions are anticipated, it is generally not economical to design shear wall buildings to remain elastic. Therefore, during a moderate to high seismic event, inelastic deformations are required as a means of reducing the 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 results in significant amount of energy dissipation and inelastic deformation [1–3]. Currently, most seismic design is carried out using prescriptive requirements that allow for a reduction in seismic design forces calculated based on elastic behavior. To account for the effect of structural ductility and energy dissipation through inelastic behavior in the United States, the calculated elastic force is divided by a force reduction factor, R, (ASCE 7 [4]), whereas, in the National ∗ Corresponding author. E-mail addresses: shedidmm@mcmaster.ca (M.T. Shedid), eldak@mcmaster.ca (W.W. El-Dakhakhni), drysdale@mcmaster.ca (R.G. Drysdale). 1 Ph.D. candidate. 2 Martini, Mascarin and George Chair in Masonry Design. 3 Professor Emeritus. Building Code of Canada (NBCC [5]), the elastic force is divided by the product of the ductility-related force modification factor, R d , and the overstrength-related force modification factor, R o . To determine the inelastic displacements corresponding to the design lateral load, the elastic displacements are then multiplied by the deflection amplification factor, C d , in the ASCE 7 [4] or by the product R d R o , in the NBCC [5]. In the ASCE 7 [4], the same R value of 5.0 is assigned to both Special Reinforced Concrete and to Special Reinforced Masonry shear wall buildings. However, in the NBCC [5], reinforced masonry shear wall construction is considered to be relatively brittle compared to reinforced concrete shear walls. In Canada, the shear wall category designations are different. The most ductile masonry shear wall system (Moderately Ductile Shear Walls) is assigned an R d value of 2.0 and R o of 1.5. On the other hand, the Canadian code assigns an R d value of 3.5 and R o value of 1.6 for reinforced concrete buildings falling within the Ductile Wall category. Therefore, a reinforced concrete shear wall building is designed for 54% of the lateral load on a similar masonry building following the Canadian code, whereas, following the American code design, the lateral load will be similar The response modification factors were generally based on engineering judgment and on observation of the performance of different structural systems in previous strong earthquakes [6]. Little information is available to justify the use of these values and 0141-0296/$ – see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.engstruct.2009.03.006 Please cite this article in press as: Shedid MT, et al. Behavior of fully grouted reinforced concrete masonry shear walls failing in flexure: Analysis. Engineering Structures (2009), doi:10.1016/j.engstruct.2009.03.006