基于纤维梁模型的钢筋混凝土箱梁非线性分析

为了准确模拟钢筋混凝土箱梁的非线性受力性能,采用精细化的三维纤维梁单元模型,基于有限元软件ABAQUS的Standard求解模块,用FORTRAN语言编制了钢筋和混凝土纤维梁单元材料用户子程序,详细介绍了建模过程。以钢筋混凝土简支箱梁为算例,对其进行全过程非线性仿真分析,并与试验结果进行对比,研究配筋率及加载方式对箱梁全过程受力性能的影响。计算结果表明:有限元分析得到的跨中荷载-挠度曲线反映了钢筋混凝土箱梁的受力全过程及破坏形态,且与试验结果吻合良好,验证了本文建模方法的可靠性;配筋率对箱梁的极限承载力影响很大,选择合适的纵筋和箍筋配筋率极为重要;不同加载方式下箱梁的受力性能是有差别的。提出了箱梁全过程受力特性的弯矩-挠度简化计算模型,并与试验结果对比,验证了本文简化计算方法的正确性,为既有桥梁的安全性和可靠度评估提供了简化方法。

Nonlinear Analysis of RC Box Girder Based on Fiber Beam Model

In order to accurately simulate the nonlinear mechanical behavior of reinforced concrete box girder,a ref ined three-dimensional f iber beam element model was adopted in the standard module of ABA Q US software,a user subroutine of rebar and concrete written in FORTRAN language was developed for f iber beam element,and the modeling process was introduced in detail.For an example of reinforced concrete simply supported box girder,the whole process nonlinearity was simulated and compared with the experimental results.And the inf luence of reinforcement ratio and loading modes on the whole process mechanical behavior was studied.The calculation results show that the load-def lection curve obtained with f inite element is agreed well with the experimental result,including the force whole process and failure mode,so the modeling method in this paper is reliability.The reinforcement ratio has a great inf luence on the ultimate bearing capacity,so it is very important to choose the proper reinforcement ratio of the longitudinal bars and stirrups.The mechanical behavior of box girder under different loading modes is different.A simplif ied calculation model of moment-def lection of box girder is proposed,and the correctness of the method is verif ied by compared with the test results,which provides a simplif ied method for the safety and reliability evaluation of existing bridges.