Numerical simulation of the shear behaviour of reinforced concrete rectangular beam specimens with or without FRP-strip shear reinforcement
The successful validation of a numerical model is presented that can realistically approximate the shear behaviour of reinforced concrete (R/C) rectangular beams strengthened against shear with externally applied open hoop fibre reinforcing polymer (FRP) strips. For this purpose, the measured load-deformation response of ten (10) full-scale R/C beam specimens is utilised. These specimens were loaded monotonically in a four-point bending arrangement up to failure. Open hoop FRP strip shear reinforcement was applied externally to upgrade the shear capacity of eight (8) R/C beam specimens. Four of these specimens had these FRP strips without anchorage, whereas for the other four the FRP strips were attached together with novel anchoring devices. This successful numerical simulation predicts with a very good degree of approximation the observed load-deformation behaviour and the ultimate shear capacity of all these specimens as well as the observed modes of failure including diagonal concrete cracking, debonding of the FRP strips in the case of no anchoring, or the plastification of parts of the anchoring devices plus the adjacent crushing of the concrete.
EXPERIMENTAL AND NUMERICAL RESPONSE OF CFRP-STRENGTHENED CONCRETE BEAMS WITH LOW OR MEDIUM STEEL CORROSION
The present study deals with the validation of a numerical model that can approximate the flexural behavior of corroded reinforced concrete beams patch repaired and strengthened with carbon fiber reinforced polymer (CFRP). Six reinforced concrete beams were corroded under an accelerated corrosion technique to low and medium corrosion levels respectively. Two beams were used as control, while the remaining four were patch repaired and strengthened with externally bonded reinforcement (EBR) and near surface mounted reinforcement (NSM) with equivalent axial rigidity. After repairing the concrete substrate and subsequent bonding of the CFRP reinforcement, the beams were tested to failure under fourpoint loading. The developed 3D finite element models take into account the different mechanical properties and detailing of corroded bars and of the mortar patch as well as of the existing concrete – mortar patch interface and of the NSM or EBR FRP – mortar patch interface. The FE analyses may reproduce the observed modes of failure including crushing of the concrete after steel yielding and debonding of CFRP. The analytical load-deflection curves compare well with the experimental flexural behavior of the corroded RC beams patch repaired and strengthened with EBR and NSM CFRP laminates. 343 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2017) 343-352 © 2017 The Authors. Published by Eccomas Proceedia. Peer-review under responsibility of the organizing committee of COMPDYN 2017. doi: 10.7712/120117.5424.18015
A study on shear reinforcement of reinforced concrete beams externally bonded with carbon fiber sheets
This paper presents the results of a study on shear reinforcement of reinforced concrete (RC) beams strengthened with carbon fiber (CF) reinforced plastics sheets. The CF sheets are externally bonded on both sides of the beam using epoxy resin adhesive. Six RC beam specimens are tested under antisymmetric bending load. Some specimens are crack-damaged by pre-loading, or crack-damaged and afterwards repaired by injecting epoxy resin into the cracked parts. A simple analysis of shear transfer in the strengthened beam is performed by using the truss model to evaluate shear-reinforcing effects of the CF sheet. The result indicates that the ultimate shear strength of the strengthened beam is about 1.3 to 1.8 times higher than that of the virgin beam, and the shear-reinforcing effect of the sheet can be fairly well predicted by the analysis using the truss model and the bond test results of concrete members strengthened with the CF sheets.