Experiment on shear performance of RC beams strengthened with FRP-ECM under secondary load
In order to study the effect of secondary load on the shear performance of reinforced concrete(RC)beam strengthened with fiber reinforced polymer(FRP)rigid grid-epoxy cement mortar(ECM)composite,a four-point bending static load test was carried out on seven RC beams under secondary load,and the pre-loading amplitude,FRP grid size and grid arrangement range were taken as parameters.The crack development process of each test beam was observed,and the mid-span deflection,stirrup strain and FRP grid strain were analyzed.Based on the truss-arch theoretical model,the pre-damage influence coefficient was introduced to calculate the oblique shear capacity of the FRP rigid grid-ECM reinforced beam.The results show that compared with the unreinforced beam,the maximum increases of mid-span deflection,main inclined crack formation load and ultimate load of the reinforced beam under ultimate load are 28.0％,37.0％and 22.5％,respectively.Compared with the reinforced beam without preload,with the increase of preload amplitude,the development of inclined cracks in the bending shear zone of the reinforced beam is faster and the maximum reduction of the peeling failure load of the reinforced layer is 8.7％.Compared with the strengthened beam with a preload amplitude of 40％Pu,the load of the FRP grid of the strengthened beam with a preload amplitude of 60％Pu and 80％Pu is reduced by 200 kN and 270 kN respectively when the FRP grid enters the shear state.The cracking load of the inclined section is increased by 22.2％and 14.8％respectively by 100 mm grid spacing reinforcement and bending shear zone transverse reinforcement.The RC beam reinforced with FRP rigid grid-ECM can effectively inhibit the propagation of oblique crack and improve the ductility during shear failure.The calculation results of the proposed shear capacity calculation formula are in good agreement with the experimental results,which can effectively predict the shear capacity of RC beams strengthened with FRP rigid grid-ECM under secondary loading.
万方数据
维普
