钢管混凝土拱的面外徐变稳定性分析

Out-plane creep stability of concrete filled steel tubular arches

摘要:

为研究混凝土徐变对钢管混凝土拱面外稳定的影响,提出了一种面外徐变稳定的数值分析方法,该方法将混凝土徐变分析的修正龄期有效模量法和有限单元法进行结合,通过引入时变的初始几何缺陷描述钢管混凝土拱在任意时刻的徐变变形,并将该缺陷引入有限元模型求解面外徐变稳定承载力．基于该方法,以已有的钢管混凝土拱试验模型为基本研究对象,讨论了持荷水平、长细比、矢跨比、横向扰动力、截面含钢率和混凝土加载龄期对面外徐变稳定承载力的影响．计算结果表明:该方法具有较好的有效性和适用性;不同参数对钢管混凝土拱面外稳定承载力影响的差异较大,其中长细比、截面含钢率和混凝土加载龄期的影响较大,而矢跨比和横向扰动力的影响相对较小;徐变导致钢管混凝土拱面外稳定承载力的降低幅度可达13.8％,设计时应予以考虑．

Abstract:

To investigate the influences of concrete creep on the out-plane stability of concrete-filled steel tubular (CFST) arches, a numerical method was presented for the out-plane creep stability analysis. The method combined the age-adjusted effective modulus method (AEMM) for the creep analysis and the finite element method for the structural analysis. The time-dependent initial geometric imperfection was introduced to express the creep deformation of CFST arches at any time. Then the out-plane creep stable bearing capacity could be obtained via the finite element analysis. Based on the method, an existed experimental CFST arch model was taken as a basic researching object, and the influences of the loading levels, slenderness ratios, rise-to-span ratios, lateral loads, steel ratios and loading ages on the out-plane creep stable bearing capacity were discussed. The results show that the method is of good efficiency and applicability; the slenderness ratios, steel ratios and loading ages have great influences on the creep stability, while the rise-to-span ratios and lateral loads have little influence; the creep-induced decreased degree of out-plane creep stable bearing capacity could rise to 13.8％ which should be concerned in design.