Abstract
This paper presents a study on a retrofit technique for masonry infilled reinforced concrete (RC) frames. The proposed retrofit technique involves the addition of reinforcing steel bars into epoxy-filled pre-cut grooves on the surface of infill walls. The feasibility of the developed technique is initially investigated experimentally through pull-out tests conducted on near-surface mounted (NSM) reinforcing steel bars. The experimental results are used to augment an existing nonlinear finite element modeling approach used to simulate the response of RC frames with the retrofitted infill panels and to calibrate the numerical models developed. The nonlinear finite element models employ smeared-crack and zero-thickness cohesive-crack interface elements to model the RC members and masonry infills, while nonlinear truss elements are used to model the reinforcing steel bars. The modeling scheme is used to numerically simulate the performance of one- and two-bay infilled RC frames with a variety of reinforcing steel retrofit configurations under lateral loads. The results indicate that the retrofit solution can improve the deformation capacity of existing infilled frames, and its effectiveness depends on the orientation and the distribution of the NSM reinforcement steel bars that are added to the infill panels.
Highlights
Many past earthquakes caused catastrophic failures of reinforced concrete (RC) frames with unreinforced masonry (URM) infill walls such as the 2009 Mw 6.3 L’Aquila (Italy) earthquake (Kaplan et al, 2010) and the 2015 Mw 7.8 Gorkha Nepal earthquake (Barbosa et al, 2017; Varum et al, 2018)
When the proposed retrofitting scheme is applied to an infill wall, the ends of the bars are anchored to the bounding RC frame, as shown in Figure 2 using drilled holes filled with epoxy
A retrofit solution for URM infilled RC frames that involves the use of near-surface mounted (NSM) reinforcing steel bars is proposed in this paper
Summary
Many past earthquakes caused catastrophic failures of reinforced concrete (RC) frames with unreinforced masonry (URM) infill walls such as the 2009 Mw 6.3 L’Aquila (Italy) earthquake (Kaplan et al, 2010) and the 2015 Mw 7.8 Gorkha Nepal earthquake (Barbosa et al, 2017; Varum et al, 2018). Experimental studies by Dizhur et al (2014) illustrate that the utilization of NSM bar retrofits can increase the out-ofplane flexural capacity of URM walls (Valluzzi et al, 2005; Haach et al, 2011; Dizhur et al, 2017; Soti and Barbosa, 2019). These studies consider bare masonry walls, retrofitted with the NSM reinforcing steel bars. There are no studies investigating the seismic performance of masonry infill RC frames retrofitted with NSM reinforcing steel bars
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