高强钢绞线网/ECC加固RC梁二次受力试验

Experiment on RC beams strengthened with high-strength steel strand meshes and ECC under secondary load

高强钢绞线网/工程水泥基复合材料(Engineered cementitious composites,ECC)作为新型高性能复合材料,充分利用了高强钢绞线网及ECC优良的力学性能,具有超高延性、韧性、优异的裂缝控制能力及强度高等优点。为探究二次受力对该新型复合材料加固钢筋混凝土(Reinforced concrete,RC)梁受弯性能的影响,本文考虑是否持载加固、原梁损伤程度、纵向高强钢绞线配筋率的影响,进行了高强钢绞线网/ECC加固RC梁受弯试验,分析了二次受力对加固梁受弯性能的影响机制,探明了各影响因素对持载加固RC梁受弯性能的影响规律。结果表明:采用高强钢绞线网/ECC持载加固RC梁,使原梁承载力、刚度、延性、韧性分别提升了38%~65%、20%~81%、0%~18%、33%~116%,且能很好约束RC梁裂缝而减小裂缝宽度;相比于卸载加固梁,持载加固梁的加固层由于存在明显应变滞后,对原梁混凝土裂缝约束效果变差,其受弯承载力、刚度、韧性有所降低,但其延性有所提高;持载加固梁的受弯承载力、刚度、延性、韧性随原梁损伤程度增加而降低,而随钢绞线配筋率的适当提高而增大。

As a new type of high performance composite material,high-strength steel wire strand(HSWS)meshes reinforced engineered cementitious composites(ECC),which makes full use of the excellent mechanical properties of HSWS meshes and ECC,has the advantages of ultra-high ductility and toughness,excellent crack-control ability and high strength.In order to explore the effect of secondary load on the flexural behavior of reinforced concrete(RC)beam strengthened with this new composite material,the bending test of RC beams strengthened with HSWS meshes reinforced ECC was conducted,considering the effects of strengthening in load-carrying state,damage degree of the original beam,and reinforcement ratio of longitudinal HSWS.The influence mechanism of secondary load on the flexural performance of strengthened RC beams was analyzed,and the influence laws of these factors on the flexural behavior of RC beams strengthened with HSWS meshes reinforced ECC in load-carrying state were explored.The results show that the flexural capacity,stiffness,ductility and toughness of RC beams strengthened with high-strength steel wire meshes reinforced ECC in load-carrying state are increased by 38%-65%,20%-81%,0%-18%and 33%-116%,respectively,and the crack development of RC beam can be well restrained,and the crack width can be reduced.Compared with the RC beams strengthened in unloading state,the beams strengthened in load-carrying state exhibit obvious strain hysteresis in the reinforcement layer,resulting in the worse constraint effect on the crack of the original beam,and its flexural capacity,stiffness and toughness decrease,but its ductility is improved.The flexural capacity,stiffness,ductility and toughness of the beams strengthened in load-carrying state decrease as the original beam damage degree increases,but grow as the reinforcement ratio of HSWS increases properly.