Vol.:(0123456789) 1 3 Iranian Journal of Science and Technology, Transactions of Civil Engineering https://doi.org/10.1007/s40996-020-00349-1 RESEARCH PAPER A New Procedure for Determination of Lateral In‑plane Failure Modes of Reinforced Concrete Squat Shear Walls Sina Sohrabi 1  · Mahmoud‑Reza Banan 1  · Mohammad‑Reza Banan 1  · Arya Zamiri 1 Received: 30 September 2019 / Accepted: 21 January 2020 © Shiraz University 2020 Abstract Reinforced concrete squat shear walls (RCSSWs) are structural elements commonly used in low-rise buildings and as bridge pier-walls and building basement walls. RCSSWs lateral in-plane failure modes are diagonal tension, diagonal compression, and sliding shear, where all are shear dominant. Determination of these failure modes is especially required for seismic design and evaluation of RCSSWs. A new procedure for such determination is introduced based on modeling the wall as a two- dimensional cracked reinforced concrete element modeled using the disturbed stress feld model. This procedure considers the stress states of concrete and main rebars according to the shear dominant lateral nature of each failure mode of RCSSWs. The main stress-related behavioral indicators and their selected thresholds are presented. The accuracy and robustness of the proposed failure mode determination procedure is tested against 12 experimental cyclic test results. High accuracy and robustness are observed for determining diferent lateral in-plane failure modes of RCSSWs. Keywords Reinforced concrete squat shear wall · Lateral in-plane failure modes · Diagonal tension failure · Diagonal compression failure · Sliding shear failure 1 Introduction Reinforced concrete squat shear walls (RCSSWs) are used as a part of lateral load resisting system while carrying verti- cal loads. RCSSWs are structural elements commonly used in low-rise buildings and as bridge pier-walls and building basement walls. Lateral load resistance of these walls var- ies in service earthquake versus the design earthquake. In the former, the lateral load resistance role is implicated by limitation of stress and displacement development in other structural members. Whereas in the design earthquake, the lateral load resistance is procured by sufcient strength and ductility of the shear wall member. One of the most impor- tant characteristics of these types of shear walls is their high initial stifness, causing the whole structure to have high stifness and relatively small period of vibration. Conse- quently, high amounts of seismic shear demands following a dominant shear failure will be induced, upon the entire structure. For shear walls to be called squat, the height to length aspect ratio must be less than two (Gulec and Whit- taker 2009; Paulay and Priestley 1992). Due to low aspect ratios of RCSSWs, low bending stresses occur under lateral demands. Consequently, the dominant failure mode of these walls is deemed as shear failure. Shear failure modes are brittle and exhibit low duc- tility and energy dissipation. Three lateral in-plane modes of shear failure can be identifed in RCSSWs which are diago- nal tension (DT), diagonal compression (DC), and sliding shear (SS) modes (Paulay and Priestley 1992). Since 1950, various researchers have experimentally investigated the lateral behavior of RCSSWs (Maier and Thürlimann 1985; Tran 2012; Luna 2016; Synge 1980; Terzioglu et al. 2018; Beko et al. 2015; Trost 2017). Ter- zioglu et al. (2018) investigated 11 RCSSWs with difer- ent response measures, namely the failure mode and lateral load capacity for a variety of design parameters including wall aspect ratio, amount of horizontal and vertical rein- forcements, and axial load. Trost (2017) studied sliding of RCSSWs in three scales: at the local scale for the compres- sion zone of cracked concrete, at the wall scale, and at the structural scale. He proposed a new sliding model validated and verifed through experimental results. This model helps understanding the nature of RCSSWs’ sliding shear failure. * Mahmoud-Reza Banan bananm@shirazu.ac.ir 1 Department of Civil and Environmental Engineering, Shiraz University, Shiraz, Iran