长期受弯构件应力应变分布及变形规律研究

Research on the Time-dependent Stress-strain and Deformation of Bending Element

通过全面考虑混凝土徐变收缩、裂缝影响及应力重分布变化过程,推导了适于不同应力分布条件下钢筋混凝土受弯构件截面长期应力应变分布规律的计算方法.提出了钢筋混凝土构件收缩翘曲变形影响系数曲线及曲率计算公式,并建立了分析预测受弯构件初始及长期总变形的通用分析方法.考虑截面非线性应力分布曲线,对各类受弯构件长期徐变收缩效应及变形进行分析,通过了试验验证.研究归纳了配筋率、截面尺寸等影响受弯构件长期挠度变化规律的主要因素.分析表明,钢筋能有效约束受弯构件长期徐变变形,而收缩翘曲变形大小及方向则主要取决于拉、压钢筋配筋率比值;在同等的初始抗弯刚度或截面积条件下,宽扁梁长期变形增长较普通梁显著.

Through the full consideration of concrete creep, shrinkage, crack and stress redistribution, a practical method to analyze long term stress-strain distribution of reinforced concrete bending elements was presented to fit for different hypothesis of stress distribution. A curve of influence parameter about the shrinkage warping of reinforced concrete elements was summed up and drawn. And the general calculation methods for the initial and time-dependent total deformation of bending elements were set up. The formulas were compiled to study the time-dependent effects and the deflection of different types of bending elements, and were verified with the experiment results. Primary influencing factors of the time-dependent deformation, such as reinforcing ratios and sectional types, were investigated. The results have shown that reinforcement can effectively limit the long term creep deformation, while the shrinkage warping depends on the ratio of tension and compression reinforcement. And with similar initial stiffness or section area, the time-dependent deformation of wide-flat beams is larger than conventional heams.