Experimental study on pre-damaged RC beams shear-strengthened with textile-reinforced mortar (TRM)

An experimental investigation of pre-damaged reinforcement concrete (RC) beams strengthened in shear with textile-reinforced mortar (TRM) is reported in this paper. Eight RC beams, including a control beam and seven beams strengthened with U-shaped TRM jacket, were constructed and tested under four-point bending monotonic load. The investigated parameters included (a) the reinforcement ratios of carbon textiles, (b) the predamaged degrees of the RC beam before strengthening, and (c) the levels of the sustaining load on RC beams during the strengthening process. The test results indicated that (1) TRM strengthening could completely restore the mechanical properties of the pre-damaged RC beams, and the shear capacity of the beams was increased by 18.32-67.45% after strengthening. (2) The shear capacity of the pre-damaged strengthened beams was smaller than that of the non-damaged strengthened beams with identical strengthening scheme. 3 As the sustaining load on the beams to be strengthened increased, the failure of the specimens changed from shear-compression mode to diagonal-tension mode, and the shear capacity of the strengthened beams decreased. Finally, a modified model was proposed to predict the shear capacity of TRM-strengthened beams based on the current code. This model considered the effects of the pre-damaged degree and the sustaining load level.