Strengthening RC beam–column connections with FRP strips

Abstract

Reinforced concrete connections, designed prior to the implementation of earthquake design standards, may be vulnerable to shear failure during a seismic attack. Addition of externally bonded fibre-reinforced polymer (FRP) composites can enhance not just the shear capacity but the deformation and energy absorption capacity of the connection. The majority of research studies to date have opted for complete or near-complete coverage of the joint region with FRP and have subjected the test specimens to cyclic (push–pull) loading. Such strengthening schemes and method of loading make it quite difficult to accurately monitor and hence understand the behaviour of the FRP and the concrete beneath. This paper presents results of a series of tests on the strengthening of shear deficient connections with FRP strips subjected to either cyclic or monotonic loading with the primary motivation being accurate description of the behaviour of the FRP. The tests also enable the failure modes to be more accurately reported and classified especially due to the use of monotonic loading. An analytical model is finally presented which accurately describes the mechanics of the FRP strengthening with the model predictions correlating reasonably well with the test data.

A new empirical model for shear strength of reinforced concrete beam–column connections

“…A database of 171 experimental RC beam-column connections (98 exterior and 73 interior) was compiled from the published literature (Alva et al, 2007;Antonopoulos and Triantafillou, 2003;Attaalla, 2004;Au et al, 2005;Chalioris et al, 2008;Chun et al, 2009;Chutarat and Aboutaha, 2003;Clyde et al, 2000;Dhakal et al, 2005;Durrani and Wight, 1985;Ehsani and Alameddine, 1991;Ehsani and Wight, 1985;Ehsani et al, 1987;El-Amoury and Ghobarah, 2002;Fisher and Sezen, 2011;Ghobarah and El-Amoury, 2005;Said, 2001, 2002;Hwang et al, 2004Hwang et al, , 2005Ishibashi, 1993;Kaku and Asakusa, 1991;Sirkelis, 2005, 2008;Kitayama et al, 1991;Kuang and Wong, 2006;Le-Trung et al, 2010;Lee et al, 2010;Leon, 1990;Liu, 2006;Lu et al, 2012;Megget, 1974;Meinheit and Jirsa, 1977;Morita et al, 1999;Murty et al, 2003;Noguchi and Kashiwazaki, 1992;Noguchi and Kurusu, 1988;Oka and Shiohara, 1992;Otani et al, 1984;Pantelides et al, 2002;Park and Paulay, 1974;Shrestha et al, 2009;...…”

Cyclic behavior of strong beam–weak column joints strengthened with different configurations of CFRP sheets

“…The authors found that both bar slips and FRP debonding were completely controlled with appropriate anchoring systems in the form of steel profiles and plates [10,11]. The seismic performance of shear-deficient joints subjected to both cyclic and monotonic loads was also studied by Shrestha et al [12] who developed an analytical model to estimate the influence of FRP sheets in shear strengthening of RC connections.…”

Retrofitting nonseismically detailed exterior beam–column joints using concrete covers together with CFRP jacket

“…It is obvious that confinement increases the performance of RC structures. Many researchers [5,8,10,14] accepted that the increased confinement of joints caused by externally bonded FRP leads to the improvement in the performance of the repaired or strengthened RC beamcolumn connections subjected to cyclic lateral loads. However, in the previous studies, most of the retrofitting techniques were bonding FRP at the joints around square or rectangular sections of the columns and/or beams, which may give little confinement effect.…”