Abstract:
Static load tests were conducted on eight reinforced concrete (RC) beams strengthened by textile reinforced high ductile concrete (TRHDC) and one control beam to study the effect of secondary loading on the shear behavior of TRHDC-strengthened beams. The influence of the number of the textile layer, damage degree of beams, and different sustained loads on the failure mode, load-deflection curves, load-strain curves of stirrups, and load-strain curves of textile were analyzed. The results indicate that all beams fail in shear compression mode, and the debonding phenomenon is only observed in one beam. TRHDC can effectively restrain the development of shear cracks, delay the yielding of stirrups and the stiffness degradation. This strengthening method can significantly improve the shear strength and deformation capacity of RC beams by up to 67% and 54%, respectively. The strengthening effectiveness does not completely increase with the number of the textile layer increase, which is related to the utilization rate of the TRHDC layer. When the stirrup of the original beam does not reach its yielding strength, the damage degree has no obvious influence on the shear behavior of strengthened beams. On the contrary, the shear strength of strengthened beams decreases with the increase of the damage degree. The strengthening effectiveness decreases with the sustained load increasing. The completely damaged RC beams can be restored by the TRHDC with two numbers of the textile layer. A calculation formula for the shear strength of TRHDC-strengthened beams considering the secondary loading was proposed. The calculation values are in good agreement with the test results.