基于板壳单元的箱梁桥空间应力分析

Spatial Stress Analysis of Box Beam Bridge Based on Shell Element

采用8节点40自由度实体退化板壳单元编制有限元软件,对预应力混凝土箱梁桥进行空间应力分析。以某(80+150+80)m预应力混凝土连续刚构桥为例,对采用板壳单元与采用杆系单元计算预应力混凝土箱梁桥空间应力的结果进行对比、分析,板壳单元程序分析结果表明截面最大主拉应力主要出现在箱梁顶、底板与腹板交界处以及底板横向跨中附近;建议活载正应力放大系数一般可以取1.15,部分位置可取1.2～1.6,活载剪应力放大系数一般可取1.5～1.8。

The finite element software using degenerated solid shell element with 8 nodes and 40 degrees of freedom was programmed to do spatial stress analysis of prestressed concrete （PC） box beam bridge. A PC continuous rigid-frame bridge with span arrangement of （80＋150＋80） m was cited as an example, aiming at conducting contrastive analysis of the spatial stresses of the PC box beam bridge calculated respectively by using shell element and link element. The results of the analysis indicate that when the shell element is used in the calculation, the maximum tensile stress mainly occurs in the top slab of the box beam, at the connection point of the bottom slab and the webs and in the bottom slab near the midspan in transverse direction. It is suggested that the amplification factor for the normal stress induced by live loads take the value of 1.15, for some parts, the amplification factor would be 1.2- 1.6, and the amplification factor for the shear stress induced by live loads be 1.5-1.8.