Failure of wall–slab joint in unreinforced masonry building

Abstract

Investigations on buildings severely damaged due to earthquakes or explosions have indicated that unreinforced masonry buildings with simply supported precast concrete floor slabs exhibit deficiencies in resistance to progressive collapse, compared to unreinforced masonry buildings with continuous cast in situ concrete floor slabs. The collapse mechanisms observed in the two types of unreinforced masonry buildings are closely related to wall–slab joint failure. The purpose of this study is to investigate the failure behavior of wall–slab joints and the effect on the collapse of the two types of unreinforced masonry buildings. Six wall–slab joint specimens and eight grooved wall specimens, induced by partial failure of wall–slab joints, were tested under monotonic vertical and horizontal loading. Numerical models were then developed, verified, and used to perform a parametric study. It was found that the wall–slab joints failed in various modes, that is, slab failure, wall failure, and slab pullout failure. The grooved wall could fail in bending or in compression. Analyses indicated that the collapse of unreinforced masonry buildings with simply supported precast concrete floor slabs develops in both vertical and horizontal directions. However, the collapse of unreinforced masonry buildings with continuous cast in situ concrete floor slabs is prone to develop only in the vertical direction, resulting in improved progressive collapse resistance.

Experimental study on post-fire behaviour of a novel assembled wall-slab joint

“…Previous research on wall-slab joints has mainly focused on their mechanical response to earthquakes, including cast-in-place wall-slab joints (Surumi et al, 2015;Rasia Salim and Prabhakaran, 2020;Chalot et al, 2021) and assembled wall-slab joints (Wang et al, 2020b(Wang et al, , 2021aArthi and Jaya, 2020b). Studies on wall-slab joints under monotonic static loading have also been conducted (Lin et al, 2017).…”

Improving in-plane seismic response of unreinforced masonry walls using steel strips

“…Moderate to strong earthquakes cause damage to existing masonry buildings which have not been constructed to resist earthquake forces, as depicted in Figure 1 (Ahmadizadeh and Shakib, 2004; Baitao and Guixin, 2018; Baitao and Peilei, 2015; Ferreira et al, 2017; Hao et al, 2016; Jingya et al, 2013; Kaplan et al, 2010; Lin et al, 2017; Okamura et al, 2015; Oyarzo-Vera et al, 2017; Preciado and Orduna, 2014; Tama et al, 2013; Wenfeng et al, 2017). Worldwide, various techniques have been proposed and applied for seismic retrofitting of unreinforced masonry (URM) walls such as reinforcement centercore, confinement with reinforced concrete (RC) strips, adding RC layers, fiber-reinforced polymer (FRP) layers, fiber-reinforced cementitious composite shotcrete, twisted stainless steel near surface mounted (TSNSM), post-tensioning, and external reinforcement.…”