预应力混凝土梁时随全过程分析

Time-dependent Finite Element Analysis of Prestressed Concrete Beams

利用通用商业有限元软件ABAQUS提供的用户子程序UMAT,采用Fortran语言编程对ABAQUS进行二次开发,将反映混凝土徐变性能的本构方程引入ABAQUS,从而实现预应力混凝土梁长期性能的有限元分析计算,并已得到已有试验结果验证。总结了预应力混凝土梁长期性能的关键影响因素,并对多根试件进行设计和参数分析,重点考察跨中截面上下缘应力差、混凝土等级、预应力筋初始有效应力大小、预应力筋种类和面积、普通钢筋配筋率等对其长期性能的影响规律。在此基础上,提出了考虑多因素影响的预应力混凝土梁长期变形简化计算公式。基于已有研究者的实验室试验与现场试验结果,对本文计算公式及国内外规范的计算公式进行了验证与对比,结果表明:本文公式计算值与试验结果的平均误差在10%以内。

Based on ABAQUS general finite element software,UMAT Fortran subroutine is compiled to estimate the long-term deflections of prestressed concrete beams,and the calculated values using the software correspond well with the laboratory results. By generalizing key parameters impact on long-term deflections of prestressed concrete beams,time-dependent finite element analysis is conducted. Taking stress differences between the upper and lower fibers of the midspan sections,concrete grade,effective prestressing tensile force,type and area of prestressed tendon and reinforcement ratio for nonprestressed compression steel reinforcement into account into account,a simplified formula for long-term deflection of prestressed concrete beam at midspan is suggested. And the calculated values using the suggested formula correspond well with the laboratory and filed test results. The errors are within 10%.