Journal of Earthquake Engineering, 20:1342–1369, 2016 Copyright © Taylor & Francis Group, LLC ISSN: 1363-2469 print / 1559-808X online DOI: 10.1080/13632469.2016.1140097 Seismic Performance Assessment of Slender T-Shaped Reinforced Concrete Walls ZHONGWEN ZHANG and BING LI School of Civil and Environmental Engineering, Nanyang Technological University, Singapore T-shaped slender reinforced concrete (RC) structural walls are commonly used in medium-rise and high-rise buildings as part of lateral force resisting system. Compared to its popularity, experimen- tal results on seismic performance of these walls are relatively sparse, especially for data regarding these walls in the non-principal bending directions. This article aims at providing additional experi- mental evidence on seismic performance of T-shaped RC structural walls. Experimental results of six T-shaped RC walls were presented. These walls resemble the structural walls found in existing build- ings in Singapore and possess slightly inferior details compared to the requirements of modern design codes. The test variables were the loading direction and the axial load ratio. The experimental results were discussed in terms of the failure mechanisms, cracking patterns, hysteretic responses, curvature distributions, displacement components, and strain profiles. In addition, the experimental results were compared with methods commonly adopted in current design practice including the nonlinear section analyses, shear strength models and effective width of the tension flange. The experimental data illus- trate that the shear lag effect not only was not accurately accounted for by the effective width method but also significantly affected the strength and stiffness of the tested specimens. Keywords T-shaped Walls; Ductility; Reinforced concrete; Seismic 1. Introduction Slender non-rectangular RC walls are one of the most structural elements in RC build- ings. Due to their large stiffness, these walls are expected to resist majority of the lateral force imposed by a possible earthquake event. Several research programs demonstrated that some issues vital to seismic performance of these walls remained insufficiently addressed, including the shear lag effect [Hassan and El-Tawil, 2003], deformation component and behavior of the wall in multiple loading directions [Thomsen IV and Wallace, 2004; Beyer et al., 2008a, 2008b; Aaleti, 2013; Sengupta and Li, 2014, 2015; Li et al., 2015]. The shear lag effect is induced by the shear flows between the flange and web segments of the wall. Due to the shear deformation of the segments, the longitudinal displacement in parts of the web and flange away from the web flange joint will lag behind the joints [Kwan, 1996]. Compared to rectangular RC walls which have been extensively researched [Paulay and Priestley, 1992; Wood, 1990, 2001; Wallace, 2004], experimental data regarding these walls are limited, and most are derived from specimens designed with good ductility. For non-rectangular walls with inferior detailing commonly found in conventional structures, their vulnerability to possible earthquake loadings remains unclear. Received 26 May 2015; accepted 5 January 2016. Address correspondence to Bing Li, School of Civil and Environment engineering, Nanyang Technological University, Singapore 639798. E-mail: cbli@ntu.edu.sg Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ueqe. 1342