考虑收缩、徐变及开裂影响的组合梁长期受力性能研究(Ⅱ)——理论分析  

Long-term behavior of composite beams with shrinkage,creep and cracking(Ⅱ):theoretical analysis

作　　者：樊健生[1] 聂鑫[1] 李全旺[1] 

机构地区：[1]清华大学,北京100084

出　　处：《土木工程学报》2009年第3期16-22,共7页China Civil Engineering Journal

基　　金：国家自然科学基金(50408001);长江学者和创新团队发展计划(IRT00736)

摘　　要：混凝土的收缩徐变效应对钢-混凝土组合梁的应力、内力、变形等长期受力性能有重要影响。建立了考虑混凝土收缩徐变影响的组合梁长期效应计算模型并采用逐步计算法进行求解,结果与试验值符合较好。对于负弯矩作用下的组合梁,建立的可考虑混凝土开裂后应力释放及受拉刚化效应的计算模型,可有效反映收缩及荷载应力导致的混凝土开裂对组合梁长期受力性能的影响。进一步的算例分析表明,现行桥梁规范用统一的弹性模量比来计算组合梁的长期效应在某些情况下不可靠。混凝土的长期模量受混凝土龄期和收缩徐变特征的影响,针对不同的荷载形式采用不同的徐变影响系数能够有效提高换算截面法的准确度。Creep and shrinkage of the concrete in composite steel-concrete beams causes variations in stresses, internal forces and displacements. A model for calculating the creep and shrinkage effects on composite beams is presented and solved by using a step-by-step method. For beams under negative bending moment, an analytical model considering stress relaxation and tension stiffening is proposed. The results of an example calculation indicate that there are cases in which the constant modular ratio adopted in the current design code is not valid, and that adoption of creep influence factor in accordance with different loading conditions may improve the validity of the transform section method.

关 键 词：组合梁 收缩 徐变 有效模量 开裂 

分 类 号：TU398[建筑科学—结构工程]