高强钢绞线网增强ECC加固无损RC梁受弯承载力研究

Research on flexural bearing capacity of non-damaged RC beams strengthened by high-strength steel wire strand mesh-reinforced ECC

高强钢绞线网增强工程用水泥基复合材料(ECC)是一种高性能复合材料,可以将其用于钢筋混凝土(RC)梁抗弯加固。为研究ECC配合比、纵向钢绞线配筋率和公称直径等因素对加固梁受弯性能的影响,进行了该复合材料加固无损RC梁受弯性能试验。结果表明:高强钢绞线网增强ECC抗弯加固方法可大幅提升RC梁受弯开裂荷载、承载力、刚度及延性,并显著降低裂缝宽度;随着纵向钢绞线配筋率、ECC弹性模量和抗拉强度提高,加固梁的开裂荷载、承载力、刚度均增大;增大ECC极限拉应变可提高加固梁延性,但采用公称直径较大的钢绞线或钢绞线配筋率过大会降低加固梁延性。基于试验结果和相关力学理论,提出了高强钢绞线网增强ECC加固无损RC梁受弯承载力计算公式,计算结果与试验结果吻合良好。

A high-performance composite material, namely, high-strength steel wire strand mesh-reinforced engineered cementitious composite(ECC), was applied to flexural strengthening of reinforced concrete(RC) beams, and the flexural behavior of the strengthened non-damaged RC beams was studied experimentally. The effects of ECC formula, longitudinal strand reinforcement ratio and nominal diameter of steel strands on the flexural performance of the strengthened RC beams were studied. The results show that by using this flexural strengthening method, the cracking load, load carrying capacity, stiffness and ductility of the strengthened beams greatly increase and the crack width is significantly reduced. The cracking load, load carrying capacity and stiffness of the strengthened beams increase with the increase of the longitudinal strand reinforcement ratio, the elastic modulus and the tensile strength of ECC. The ductility of the strengthened beams increases with the ultimate tensile strain of ECC. However, the ductility would be reduced due to the use of steel strands with a relatively large nominal diameter or an excessive strand reinforcement ratio. The calculation formula for the flexural capacity of non-damaged RC beams reinforced by high-strength steel wire strand mesh-reinforced ECC is proposed based on the test results and the theories of mechanics, and the calculation results are in good agreement with the test results.