预应力混凝土受弯开裂截面应力计算方法对比  

Comparison of Calculation Methods for Cracked Section Stress of Prestressed Concrete Beams

作　　者：郑毅敏[1,2] 王怀清[1] 赵勇[1] 

机构地区：[1]同济大学建筑工程系,上海200092 [2]同济大学建筑设计研究院(集团)有限公司,上海200092

出　　处：《结构工程师》2015年第3期34-39,共6页Structural Engineers

基　　金：国家科技支撑计划课题(2011BAJ10B02)

摘　　要：在平截面假定的基础上,推导了受压区混凝土法向应力图取三角形和抛物线形时,矩形截面预应力混凝土受弯构件正截面应力计算公式,并通过算例对计算结果进行了对比,同时还对比了《混凝土结构设计规范》的简化公式计算结果。算例分析结果表明,相比抛物线模式的计算结果,取用三角形模式的偏小,相对偏差平均为-8.5%,且相对偏差随有效预应力增大和混凝土强度减小而增大;而规范简化公式计算结果比抛物线模式的偏大,相对偏差平均为14.7%,且离散性较大,其离散性和相对偏差随外弯矩的减小,并随混凝土强度的提高和有效预应力增大而增大;当采用三角形模式时,采用折减弹性模量0.6Ec,可有效考虑混凝土进入塑性的影响。Formulas for calculation of normal sectional stress are deduced specially for rectangular-section prestressed RC bending members. The formulas are based on plane cross-section assumption when triangle and parabola normal stress graphic are chosen for compression zone. Compared with examples in this article and simplified equations in Code for Design of Concrete Structures, several conclusions are drawn. Analysis through comparison reveals that results from triangle model are less that from parabola model with an average relative deviation of - 8.5 % and that the deviation increases with the rise of effective prestress and the decline of concrete strength. Also found is that results from simplified equations in the code are more than that of parabola model with a large dispersion. This dispersion and the relative deviation increase with the rise of moment load, concrete strength and effective prestress. Furthermore, by adopting triangle model and 0.6Ec as a reduced modulus of elasticity, it will provide better result given the situation where plasticity exists.

关 键 词：预应力混凝土 受弯构件 正截面应力 混凝土受压本构模型 

分 类 号：TU378[建筑科学—结构工程]