混凝土应力图形简化对截面抗弯强度的影响

Effect of simplified stress graph of concrete on bending strength of its cross-section

根据混凝土受压应力应变关系的常用曲线方程,对受弯截面压区混凝土应力进行了矩形应力简化,推导得到了等效矩形应力图形高度及应力强度的一般公式。选取4种应力应变关系模型,计算得到了矩形应力图形的简化结果,并分析了单筋截面不同模型的相对抗弯强度及其与GB50010—2002《混凝土结构设计规范》(简称《规范》)建议值的相对误差。分析表明,不考虑混凝土受压的软化性能将过高估计截面的承载力,《规范》建议值导致截面抗弯强度计算值提高近5%,且在截面高配筋率下更为显著。

According to the stress-strain curve equation of concrete compression, we simplified the rectangle stress graph of the stress on the area of its bending cross-section in this paper. A general formula for the height of equivalent compression stress block and the stress strength formula were deducted. Four kinds of stress-strain relations were used to calculate the rectangle stress block simplification results. The relative error between the bending strength of a rectangular section with tension reinforcement and that given in the code GB 50010—2002 was analyzed. The results showed that the flexural strength of a cross-section would be over-estimated when the soften character of concrete was ignored. The strength given in the Code is 5% higher than that from the calculation in this paper and further higher when the ratio of reinforcement is high.