Shear Resistance of Pre-cracking Reinforced Concrete T-beam Strengthening with CFRP Sheets

摘要

Eleven pre-cracking reinforced concrete T-beams were strengthened with U-stirrups and longitudinal sheets of CFRP, the main parameters were the width, layer and space of U-stirrups of CFRP. The tests for shear resistance of the beams were carried out to measure the diagonal crack development and crack width, mid-span deflection, CFRP strain and ultimate resistance. Compared with the reference beam without strengthening, the diagonal cracks were effectively restrained and the shear resistances of the beams were also strengthened by the U-stirrups of CFRP. However, the shear resistance increment of the beams were not in direct proportion with the amount of CFRP sheet characterized by the width, layer and space of U-stirrups, as the strengthening effect is obviously influenced by the bond quality and the anchorage reliability of the U-stirrups. When strengthened with one layer, the shear resistance of the beam was enhanced largely by the wider sheet. When strengthened with two layers, the enhancement of shear resistance was weakened with the increasing width of sheets.