比拟杆法分析研究单箱三室箱梁剪力滞效应

The bar simulation methodfor shear lag effect of three-cell box girders

基于比拟杆法,推导单箱三室箱梁的比拟杆面积计算公式和剪力滞效应计算的控制微分方程。针对算例,分别采用本文理论、有机玻璃模型试验和有限元法分析简支箱梁和连续箱梁在集中力和均布荷载作用下的剪力滞效应。研究结果表明:本文理论解与有机玻璃模型试验解和板壳有限元解吻合良好。对简支箱梁,中腹板部位的顶和底板正应力均大于边腹板处顶和底板正应力。对连续箱梁,跨中截面中腹板处的顶和底板正应力均大于边腹板处和底顶板正应力。但对满跨均布荷载下的支座截面,底板正应力在边腹板部位大于中腹板部位,应力相差最大约12.91%。在单箱三室箱梁设计中考虑各腹板部位顶和底板正应力的差异,并以此确定有效翼缘分析宽度是非常必要的。

Based on the bar simulation method,the analogy bar area calculation formula and the control differen-tial equation of shear lag effect for single box and three rooms girder were deduced .Taking the single box and three rooms girder for example,the shear lag effect was analyzed using the theoretical calculation with bar simu-lation method in this paper,model test research on simply supported box girder of organic glass and the numeri-cal solution of plate and shell of simply supported box girder and continuous box girder under concentrated force and uniformly distributed load respectively.The results show that the theoretical calculation by bar simulation method in this paper is in good agreement with the other two methods mentioned above.The positive stress at roof and floor of mid-web is bigger than the stress at roof and floor of edge-web for simply supported box girder and the middle section of continuous box girder.But the positive stress at floor in the edge web site is bigger than the stress in mid -web site at the bearing section under uniform load.The greatest difference of stress is about 12.91%.Considering the difference of stress at roof and floor of each web in the bridge design,and the determi-nation of the effective flange width analysis was very necessary.