宽体单箱双室波形钢腹板箱梁桥的剪力分配研究

Shear Distribution of Double-Cell Single-Box Composite Box Girder Bridge with Corrugated Steel Webs

为明确波形钢腹板箱梁桥在实际恒载和车道荷载作用下的截面剪力分配特征,以一座宽体单箱双室三跨连续梁桥为例,采用实体有限元模型进行了分析.对该桥的分析表明:一次成桥模型中所得自重+预应力作用下的截面剪力和腹板承剪比与考虑实际悬浇施工过程的结果有较大差异,在腹板承剪分析中对恒载应考虑实际的施工方案;车道荷载中集中荷载对截面剪力的贡献在大部分截面都接近甚至超过均布荷载的贡献,并且集中荷载产生的截面剪力主要被顶底板而非腹板承担;对于所选择的特征截面,车道荷载作用下腹板承剪比分布在30.37%~51.47%之间,低于二期铺装作用下的41.99%~70.07%,但均表现为桥墩附近腹板承剪比偏低而跨中附近偏高的趋势;横向偏心车道荷载作用下的腹板剪力分配并不能简单以扭矩作用考虑其横向偏心效应,还要考虑车道荷载的局部效应,当有车道直接作用于腹板附近时会使该腹板的剪力分配明显提高.

A double-cell single-box bridge with three spans was taken as example in numerical analysis based on solid FE model to clarify the shear distribution of composite box girder bridge with corrugated steel webs under dead load and lane load.The research results show that the aggregated shear forces under self-weight and pretention got from models with and without the construction process simulated are quite different,so are the shear ratios of webs.It is suggested that practical models should be adopted for the dead load in shear distribution analysis.The point load in lane load contributes the same or even more section shear force than the line load,and the shear force produced by the point load is resisted mainly by the decks instead of the webs.In the characteristic sections,the shear ratios of webs under lane load and pavement load vary respectively between 30.37%to 51.47%and between 41.99%to 70.07%,and the shear ratios of webs always increase with the distance away from piers.For the shear distribution analysis under lane load with lateral eccentricity,the eccentricity effects could not be modeled by a torsion simply,because the eccentricity effects also show certain local effects:when the land load is located on or near a web,this web would bear much more shear than other webs.