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超高韧性水泥基复合材料(UHTCC)具有优异的抗裂和能量吸收能力,用其取代混凝土可显著提高结构的耐久性和延性。为了推广UHTCC在限裂要求严格的结构中的应用,开展了钢筋增强UHTCC受弯构件即RUHTCC梁的研究。根据RUHTCC梁受拉区UHTCC不退出工作的特点,采用弹性理论推导RUHTCC梁受弯承载力计算公式,并将计算结果与无腹筋长梁弯曲试验结果进行验证对比。结果表明:在正常使用状态下,裂缝宽度保持在0.05mm以内,满足处于高腐蚀环境下结构裂缝宽度限值要求;RUHTCC梁平截面假设成立;起裂后直至钢筋屈服,UHTCC和钢筋保持很好的变形协调性;试验结果与理论计算吻合,计算得到的延性指数偏于安全,在实际工程设计中用其来预测结构或构件的延性是合理的;与钢筋混凝土梁相比,UHTCC能够延缓钢筋屈服,提高结构或构件的承载力和延性,降低钢材用量;低配筋率有利于UHTCC材料性能的发挥。
Ultra-high toughness cement-based composites (UHTCC) have excellent resistance to cracking and energy absorption, replacing the concrete with it can significantly improve the durability and ductility of the structure. In order to popularize the application of UHTCC in the structure with strict requirements of cracking, the research of reinforced UHTCC flexural members, ie, RUHTCC beams, has been carried out. According to the characteristics of UHTCC in RUHTCC beam tension zone, the calculation formula of flexural capacity of RUHTCC beam is deduced based on elastic theory. The calculated results are compared with the results of bending test of long beam without web reinforcement. The results show that the crack width is within 0.05mm under normal use, which satisfies the requirement of structural crack width under high corrosive environment. The assumption of RUHTCC beam-plane cross-section holds, and the UHTCC and rebar remain good Deformation and coordination; the experimental results are in good agreement with the theoretical calculation, and the calculated ductility index is biased to safety. It is reasonable to predict the ductility of structures or components in actual engineering design. Compared with RC beams, UHTCC can delay the yield of reinforcement , Improve the bearing capacity and ductility of the structure or components, reduce the amount of steel; low reinforcement ratio is conducive to UHTCC material performance.