【摘要】 针对U形梁属于开口构件，其剪力滞效应不能直接套用成熟的闭口箱梁剪力滞效应的计算方法，研究了轨道交通U形简支梁的剪力滞效应。以青岛某地铁为背景，分别建立空间实体有限元模型和平面杆系模型。研究了3种不同类型荷载作用下U形梁剪力滞效应的纵横向分布规律；分析了4种结构参数变化下U形梁的剪力滞系数变化情况；计算了U形梁的有效宽度并与中国现行规范比较。研究结果表明：列车荷载是影响U形梁剪力滞系数纵向分布的主要因素，列车车轮作用位置处剪力滞效应明显；在一期恒载和二期恒载分别作用下均呈现出简支梁跨中区段剪力滞效应较小，支座区段剪力滞效应明显的规律。在剪力滞效应的横向分布中，3种荷载分别作用下U形梁道床板处的剪力滞效应均较腹板位置处明显。影响U形梁剪力滞效应增大的主要结构因素是梁高和底板宽度，其中梁高的影响显著，增加底板厚度能有效降低U形梁的剪力滞系数，而改变腹板厚度对剪力滞系数的影响甚微。目前中国规范为考虑桥梁剪力滞效应而采用的箱梁有效宽度计算不适用轨道交通U形梁，在考虑荷载类型和结构参数影响的基础上，建立的U形梁有效宽度修正计算公式与有限元模拟结果吻合良好。研究成果可为实际工程中U形梁的应力计算与钢筋配置提供参考。更多还原

【Abstract】 Aimed at U-shaped girder belongs to open structure, its shear lag effect can not be directly applied to the mature calculation method of closed box girder shear lag effect, the shear lag effect of simply-supported U-shaped girder of rail transit was studied. Based on the background of a subway in Qingdao, the finite element model of space entity and the plane bar model were established respectively. The longitudinal and transverse distribution of shear lag effect of U-shaped girder under three different load types were studied. The variation of shear lag coefficient of U-shaped girder with four kinds of structural parameters were analyzed. The effective width of U-shaped girder were calculated and compared with the current domestic specifications. The results show that train load is the main factor affecting the longitudinal distribution of shear lag coefficient of U-shaped beam, and the shear lag effect is obvious at the position of train wheels. Under the action of the first phase and the second phase of the dead load, the shear lag effect of the simply supported girder is small in the middle section and obvious in the support section. In the transverse distribution of shear lag effect, the shear lag effect at the bed plate of U-shaped girder is more obvious than that at the position of web plate under the action of three kinds of loads respectively. The main structural factors influencing the increase of shear lag effect of U-shaped girder are beam height and floor width, among which the influence of beam height is significant. Increasing the thickness of the bottom plate can effectively reduce the shear lag coefficient of the U-shaped girder, but changing the web thickness has little effect. By comparison and analysis, the current specifications for calculating the effective width of box girder are not suitable for calculating the effective width of U-shaped girder in rail transit. The effective width correction formulas of U-shaped girder is established on the basis of considering the influence of load type and structural parameters, and it is in good agreement with the finite element simulation results. The results can provide reference for stress calculation and reinforcement configuration of U-shaped girder in practical engineering. 3 tabs, 13 figs, 25 refs.更多还原