Repair and FRP Strengthening of Earthquake-Damaged RC Shallow Beam-Column Joints

Abstract

Three earthquake-resistant wide beam-column joint specimens (one interior, and two exterior) which developed beam plastic hinging mechanism and beam flexural failure under large drift reversals were repaired and FRP strengthened for restoring their structural function. The repair and strengthening technique consisted of: (i) sealing the major flexural cracks that developed within the beam plastic hinge region using epoxy injection; (ii) adding carbon fiber-reinforced polymer (CFRP) reinforcement at the top and bottom faces of the beam to control the growth of the flexural cracks, boost up the beam negative and positive flexural capacities and at the same time compensate in part for the loss in the joint lateral stiffness; and (iii) providing CFRP jacket at the potential hinging regions of the columns for confining the concrete and enhancing the bond capacity of the spliced reinforcement. The effectiveness of the upgrading technique is demonstrated by comparing the performance of the upgraded joints when subjected to lateral cyclic loading against the performance of the same joints before damage. With its simplicity in application, the upgrading technique succeeded in bringing the damaged joints back into service conditions and in restoring their flexural stiffness under lateral load which degraded due to large drift reversals.

Experimental and Numerical Research on Seismic Performance of Earthquake-Damaged RC Frame Strengthened with CFRP Sheets

“…Beamcolumn joints of RC frame also played an important role in structural stability and seismic performance, since in many cases the whole structural failure starts with joint failure. The experiments [18][19][20][21][22] demonstrate that exterior bonded CFRP sheets on RC joints can upgrade shear strength, restore structural flexural stiffness, delay the degradation of stiffness, and bring the damaged joints back into normal service. Effect of CFRP sheets has been assessed at the RC component level in terms of beams, columns, and joints.…”

Externally bonded carbon fiber–reinforced polymer composites for seismic retrofit of reinforced concrete coupling beams designed according to old codes

“…Use of EB-FRP sheets to strengthen structural elements like slabs, beams, and columns is well documented. Some experimental studies (such as Akguzel, 2011; Antonopoulos and Triantafillou, 2003; Elsouri and Harajli, 2015; Ghobarah and El-Amoury, 2005; Ghobarah and Said, 2002; Hadi and Tran, 2016; Li and Kai, 2010; Pantelides et al, 2008; Parvin et al, 2014; Quintana Gallo, 2014; Rahman et al, 2014; Vatani-Oskouei, 2010) also investigated the effectiveness of using FRP composites to retrofit beam-column joints. Nevertheless, the use of FRP for seismic strengthening of CBs and beam-wall joints of CSWs has not been fully investigated.…”