钢-混凝土组合梁混凝土收缩徐变的增量微分方法

Incremental differential modeling of creep and shrinkage of steel-concrete composite beams

为深入了解混凝土收缩徐变对钢-混凝土组合梁力学性能的影响,采用随时间变化的换算弹性模量法建立了钢-混凝土组合梁混凝土收缩徐变的增量微分模型,得到了组合梁内力、挠度和钢-混凝土界面滑移的微分控制方程.根据边界条件,给出了内力、变形及钢-混凝土界面滑移等各项力学性能指标的闭合解.为验证增量微分方法的正确性,对试验梁和算例梁进行了跨中挠度-时间曲线、沿梁高应变分布及梁端钢-混凝土界面滑移的计算分析.计算结果表明,所建立的增量微分法与试验值和其他计算方法的计算结果吻合较好,可以有效地预测钢-混凝土组合梁的长期力学性能.

In order to investigate the effect of concrete creep and shrinkage on the mechanical behavior of steel-concrete composite beams,a theoretical model,using the conversion elastic modulus method,of the long term behavior of steel-concrete composite beams is presented in this paper.The differential equations of the incremental deflections and internal forces were deduced and the general closed-form solutions for simply-supported composite beams were obtained.The calculated results of the proposed model were compared with the experimental results of steel-concrete composite beams reported and the calculated results of worked example beam in the literature.It is shown that the calculation results by the proposed method are in close agreement with the experimental results and the proposed model is capable of predicting the mechanical behavior of the steel-concrete composite beams with an acceptable degree of accuracy.