预应力混凝土梁开裂后的结构行为

Structure behavior of cracked prestressed concrete beam

为了研究预应力混凝土梁开裂后的结构非线性行为,基于Timoshenko分层梁理论,选取恰当的混凝土和钢筋的本构关系,考虑了混凝土的拉伸刚化效应和中性轴变化对预应力钢筋混凝土梁的受力、变形的影响,有效地模拟了预应力混凝土梁的开裂、屈服和失效全过程.分析了预应力混凝土梁在单调加载下的受力性能,并与试验结果进行比较.探讨了梁开裂后的刚度和截面的应力重分布现象.算例表明分层梁单元模型对于预应力混凝土梁的非线性分析有良好的适应性,对梁开裂后的使用性能评估有实际应用价值.

In order to research the non-linearity structure behavior of the cracked prestressed concrete beam, some factors were considered by using Timoshenko layered beam theory, including the constitutive equation of concrete and steel, the tension stiffening affection of concrete, and the impacts of neutral axis changing on the prestressed concrete beam＇s mechanical performance. The whole process of the prestressed concrete beam＇s cracking and crushing was effectively simulated.The nonlinear analysis results of a prestressed concrete beam model under monotonic loading were compared with the results from static test, and the stiffness and the stress redistribution were also analyzed. The results show that the layered beam model can well describe the nonlinear behavior of the prestressed concrete beams and it is valuable to evaluate the serviceability ofthe cracked beam。