基于有限混合单元法的受弯构件剪力滞效应研究

Study of Shear Lag Effect in Flexural Members Based on Hybrid Finite Element Analytical Method

为研究对称荷载下受弯构件的剪力滞效应,以某(40+90+70+300+20)m独塔自锚式悬索桥为研究对象,采用ANSYS 11.0建立全桥空间有限元模型(主跨300m钢箱梁用板壳单元模拟,其余部分用杆系单元模拟),采用TDV/RM 9.1建立全桥空间有限元杆系模型,运用有限混合单元法进行剪力滞系数和有效分布宽度计算,并与欧洲、日本规范有效分布宽度的计算值进行比较。结果表明:支点截面的正应力沿着梁宽方向变化较为剧烈,其它截面的正应力变化较为平缓,越接近支点的截面剪力滞效应越明显;受弯构件支点截面与跨中截面的有效分布宽度可通过采用该方法的计算值内插求得;欧洲、日本规范受弯构件的有效分布宽度计算值较有限元计算值偏大,且未能考虑复杂受力情况下的精确计算。

To study the shear lag effect in the flexural members under symmetrical loads, a single tower self-anchored suspension bridge with span arrangement of （40＋90＋70＋300＋20） m was taken as the study background. The ANSYS 11.0 was used to establish the spatial finite element model of the overall bridge. The steel box girder sections in the 300 m main span are modelled by plate-shell element and the remaining part was modelled by spatial link element. The TDV/RM 9. 1 was used to establish the spatial link element model of the overall bridge, the hybrid finite elment method was employed to calculate the shear lag coefficient and effective distribution width and the results were compared with the values of the effective distribution width recommen- ded in the Euro Code and Japanese Specification. The Comparison demonstates that the normal stress in the cross sections at the supports showed drastic changes along the width of the girder, and the normal stress in other cross sections varied gently, and the nearer the cross sections are to the supports, the more apparent the shear lag effect will be. The effective distribution width in the cross sections at the supports of flexural members and the midspan cross section can be achieved by interpolating the calculated values gained by this method. The values of effective distribution width in the Euro Code and Japanese Specification are bigger than the calculated values, which do not take into account the accurate calculation under complex load bearing conditions.