Seismic Retrofit of R/C T-Beams with Steel Fiber Polymers under Cyclic Loading Conditions

Abstract

This paper presents results of an experimental study on seismic response of reinforced concrete (RC) T-beams with shear deficiencies strengthened with externally bonded steel fiber reinforced polymer (SFRP) strips. Seven cantilever RC beams were strengthened with externally bonded uniaxial SFRP strips in a U-shape configuration and were tested under cyclic loading conditions. The two main variables examined were the strip spacing and the use of anchoring system. Among the investigated anchoring systems, one was patented, and it is studied in the present manuscript. The examination of the results leads to the conclusion that the anchoring system has a significantly more pronounced effect on the performance of the beams and the mode of failure than the type or spacing of the strips. Furthermore, SFRP strips seem to have a great potential to be used for shear strengthening, especially since the use of mechanical anchoring systems drastically improves their performance. On the contrary, the lack of mechanical anchoring results in premature delamination of the strengthening system, and thus an undesirable SFRP material performance.

Evaluation of Prospective Use of Existed CFRP-Strengthened Concrete Pipes in Forest Areas: Assessment of Their Structural Stability and Possible Re-Use

“…The adopted limit state of the following scenarios focused on depicting the developed strains onto the CFRP layers. We chose the aforementioned limit state since it was well known from the literature [38] that the ultimate strain capacity of CFRP ranges between 1.2-1.5%. Furthermore, the adhesive between the CFRP layers and mortar was not investigated due to the fact that the CFRP sheets were wrapped around the pipe, resulting in a perfect attachment of the composite, eliminating a debonding failure mode.…”

“…For all cases where the strengthened RC pipes were put to the test, it was shown that the exploitation of the composite material was less than 50%, resulting to increased structural stability for the pipe. well known from the literature [38] that the ultimate strain capacity of CFRP ranges between 1.2-1.5%. Furthermore, the adhesive between the CFRP layers and mortar was not investigated due to the fact that the CFRP sheets were wrapped around the pipe, resulting in a perfect attachment of the composite, eliminating a debonding failure mode.…”

Repair of Heavily Damaged RC Beams Failing in Shear Using U-Shaped Mortar Jackets

“…The aforementioned literature review reveals that the majority of the conducted research is focused on the application of nonconventional jackets in strengthening methods of original RC structural members [17][18][19]21,22,24,[26][27][28][30][31][32][33][34]36,[38][39][40][41][42][43][44][45][48][49][50]56]. Significantly fewer studies investigate such jackets for the repair of preloaded and slightly damaged RC specimens [20,23,25,29,35,37,46,47,[51][52][53][54][55].…”

“…These reasons have led researchers to switch to new jacketing techniques with alternative materials such as steel [17][18][19], advanced materials such as fiber reinforced polymer (FRP) [20][21][22][23][24][25], textile reinforced concrete or mortar [26][27][28][29] and shape memory alloys [30][31][32], cement-based materials such as ferrocement [33][34][35][36], steel fibrous concrete or mortar [37][38][39][40], high-performance fiber reinforced concrete [41][42][43][44][45][46][47][48], self-compacting concrete (SCC) [49][50][51][52][53][54], and thin slightly reinforced flowable mortar [55,56]. Many of these jacketing techniques have been proved successful substitutes to common RC jacketing.…”

Pseudo-Dynamic Analyses of Infilled Reinforced Concrete Framed Structures With Prior Damages After Advanced Retrofit

“…Available innovative materials and intervention techniques such as steel fiber systems or fiber reinforced polymers (FRPs) in the form of sheets, strips and ropes are widely used. Suitable diagnosis and retrofit of deficient members can improve their strength, delay further corrosion of the reinforcement as well as reduce deformations at the serviceability limit stage [5][6][7][8][9][10][11]17].…”