论文部分内容阅读
裂缝闭合是部分预应力砼的一个重要特性。本文根据3根先张法和6根后张法部分预应力砼矩形梁在循环荷载作用下的试验结果,分析了垂直裂缝的变化特点,提出了裂缝闭合的定义,指出了在短期循环荷载作用下影响裂缝闭合的主要因素。并分别根据砼的应力-应变关系、最大受压塑性应变及名义拉应力,提出了三种计算裂缝闭合弯矩的方法。这些方法有比较明确的物理概念,其计算值与试验结果的符合程度良好,其中的简化方法和名义拉应力方法简单实用。同时,本文还对在多次循环荷载作用下裂缝开展宽度的计算进行了探讨。
Crack closure is an important characteristic of partially prestressed concrete. Based on the experimental results of three pretensioned and six post-tensioned prestressed rectangular beams under cyclic loading, this paper analyzes the characteristics of vertical fractures, proposes the definition of fracture closure, and points out the short-term cyclic loading effects. The main factors affecting crack closure. According to the stress-strain relationship, maximum compressive plastic strain and nominal tensile stress of concrete, three methods for calculating the closed bending moment of the fracture are proposed. These methods have relatively clear physical concepts. The calculated values are in good agreement with the test results. The simplified method and the nominal tensile stress method are simple and practical. At the same time, this paper also discusses the calculation of the crack development width under multiple cyclic loads.