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UHTCC(ultrahigh toughness cementitious composite)是一种超高韧性新型水泥基复合材料,具有应变硬化的受拉特性和优良的裂缝分散能力,可显著提高结构的力学性能和耐久性,被有关权威专家认为对防裂、限裂及抗震要求较高的结构能极大提高其耐久性和抗震性,具有重大的突破意义和较广泛的推广应用前景.本文着眼于该新型材料,研究了钢筋增强超高韧性水泥基复合材料即RUHTCC梁的弯曲性能.以平截面假设为依据,根据物理方程、变形几何方程以及力与弯矩的平衡方程,导出了RUHTCC梁从加载开始到极限破坏整个过程中受压区按折线应力分布图计算的正截面承载力基本方程,并给出了便于工程设计的按等效矩形应力分布图计算的简化公式,确定了等效矩形中两个等效参数的取值,并进一步推出了界限配筋率、正截面抗弯刚度以及韧性指数的计算公式.进行了两组不同配筋率的RUHTCC梁和普通钢筋混凝土RC梁的弯曲试验,结果与理论公式较为吻合,延性指数试验值与计算值存在一定差异.与RC梁的比较发现,RUHTCC梁有高的承载力、延性和控裂能力,且配筋率越小,其提高的幅度越大.
UHTCC (ultrahigh toughness cementitious composite) is a new type of ultra-high toughness cement-based composite material with strain-hardening tensile properties and excellent crack dispersion, can significantly improve the mechanical properties and durability of the structure, the relevant authoritative experts believe that Cracking, cracking and higher seismic requirements of the structure can greatly improve its durability and seismic resistance, has a major breakthrough in the significance and wider application of the promotion.This paper focuses on the new material, studied the reinforcement of ultra-high toughness Based on the assumption of the cross-section and physical equations, deformation geometry equation and balance equation of force and bending moment, the rupture behavior of RUHTCC beam is deduced from the loading start to the ultimate failure According to the tortuosity stress distribution diagram, the basic equation of the normal section bearing capacity is given, and the simplified formula for calculating the equivalent rectangular stress distribution diagram which is easy for engineering design is given. The values of two equivalent parameters in the equivalent rectangle are determined. The calculation formula of the limit reinforcement ratio, the normal section flexural rigidity and the toughness index are further introduced.The two groups of different reinforcement ratio The bending tests of RUHTCC beams and ordinary RC beams show that the results are in good agreement with the theoretical formulas and there is a certain difference between the ductility index and the calculated values.Compared with the RC beams, the RUHTCC beams have high bearing capacity, ductility and crack control ability , And the smaller the reinforcement ratio, the greater the extent of its increase.