基于实体退化虚拟层合单元预制桥墩承载力分析

Analysis of Capacity of Prefabricated Bridge Pier Based on Degenerated Solid Virtual Laminated Elements

以某跨海桥梁工程中采用的埋床法施工的预制墩台为研究对象,该预制墩台的承载能力是设计的重点,设计阶段需对不同荷载工况下的墩台承载能力进行精细分析。墩台承载能力分析需要考虑混凝土和钢筋两种不同材料的非线性,并考虑预应力筋的作用。一般的有限元程序在处理材料非线性问题时往往存在计算效率低、计算成本高、计算不收敛等问题。实体退化序列单元,该单元基于经典的三维实体等参元和梁、板壳理论简化假定得出,在保证计算精度的前提下,该单元更为简单、高效。采用该单元对施工过程中桥墩墩身进行了承载力分析,并对其安全性进行了评估。分析结果表明,桥墩在关键荷载工况下,其正常使用状态的钢筋应力处于较低水平,关键部位混凝土未出现裂缝,对结构安全、耐久性无影响,结构承载力满足要求。

The prefabricated bridge pier constructed by buried bed method in a sea -crossing bridge project is studied. The load-bearing capacity of the prefabricated bridge pier is of great significance in the design, and needs to be delicately analyzed for different loading conditions. The nonlinearity of concrete and reinforcement, and the effect of pre-stressed tendons need to be considered. However, using generalized finite element program leads to low efficiency, high cost and no convergence in nonlinearity treatment of material. Therefore, a degenerated solid element based on traditional 3D solid isoparametric element and simplifying assumption in beam theory and shell theory. This element is more simple and efficient without losing the computational precision. It is used for analyzing the load-bearing capacity of the prefabricated bridge pier and evaluating the safety. The result indicates that the stress in rebar is relatively low in normal service state and no crack formed in concrete of the critical part, which are no influence on the safety and durability of the structure. The ultimate load capacity of piers meets the construction requirement.