多肋式梁桥在全过程中应力重分布研究

Stress redistribution analysis of multi-girder structure during the whole course

摘要:

为了考察多肋式梁在全过程中受力性能,利用非线性实体退化壳单元理论研究了多肋式梁的应力重分布规律.混凝土和普通钢筋采用分层壳单元模拟,预应力钢筋采用组合壳单元模拟,推导了预应力钢筋对组合壳单元刚度矩阵的贡献和统一的非线性壳单元模式.利用Owen屈服准则、Hinton压碎准则和弹塑性强化模型考虑了混凝土和钢筋的非线性效应,有效模拟了预应力混凝土多肋式梁的开裂、屈服和失效全过程,并编制了相应的三维非线性全过程计算程序.结合破坏性试验资料可知,理论计算结果与试验数据吻合良好,并对预应力钢筋应力发展规律进行研究.结果表明,用实体退化壳单元模拟预应力混凝土多肋式梁是合适的,研制的非线性单元和非线性程序是正确的.

Abstract:

In order to grasp the mechanism of the multi-girder structure during the whole course,the stress redistribution regularity is studied with shell element degraded from solid element.Steel and concrete are depicted by layered shell element and the prestressed steel is modeled by combined shell element.Then the stiffness matrix of contribution of the prestressed steel to the combined shell element is deduced.Respectively based on Owen yielding theory and Hinton crushing theory and bilinear model,the material nonlinear properties of concrete and steel are considered.Then the procession of cracking,yielding and failure of prestressed concrete multi-T girders is imitated and the analytical procedure is compiled.Through compared with the failure experiment results of a prestressed concrete multi-T girder bridge,the calculations are in good agreements with them.The regularity of stress redistribution of prestressed steel is studied.It shows that it is feasible to apply shell element degraded from solid element to depict the prestressed concrete multi-T girder bridge and the corresponding computational method and procedure for nonlinear whole-course analysis are correct and reliable.