带UHPC组合桥面板的连续组合钢箱梁桥剪力滞效应分析

Analysis on Shear Lag Effect of Continuous Composite Steel Box Girder Bridge with UHPC Composite Deck

针对采用钢-UHPC组合桥面板的大跨连续组合钢箱梁桥在UHPC层浇注后及运营阶段桥面应力分布不均匀的问题,基于ANSYS采用混合单元模型研究了钢箱梁及组合钢箱梁的剪力滞效应。分别选取了连续钢箱梁在自重及UHPC层湿重作用下、连续组合钢箱梁在近期组合作用下的2种工况,分析了中跨跨中区域、中支点区域的UHPC板、钢顶板及钢底板的纵向正应力沿横桥向的分布及其相应的剪力滞系数的分布。结果表明:无横隔板截面的UHPC板、钢顶板、钢底板的纵向正应力及剪力滞系数沿横桥向的分布规律一致;有横隔板截面的UHPC板、钢顶板、钢底板的纵向正应力及剪力滞系数沿横桥向的分布规律一致;无横隔板截面的UHPC板、钢顶板、钢底板在中腹板、边腹板及挑臂腹板均表现出负剪力滞效应,有横隔板截面的UHPC板、钢顶板、钢底板在中腹板、边腹板及挑臂腹板均表现出正剪力滞效应。

Aiming at the problem of uneven stress distribution on the deck of long-span continuous composite steel box girder bridge with steel UHPC composite deck after UHPC layer pouring and at operation stage,the shear lag effects of steel box girder and composite steel girder are analyzed based on hybrid element model in ANSYS.Selecting the working conditions of the steel box girder under self-weight and wet weight of UHPC layer and the composite steel girder under recent combination,the distribution of longitudinal normal stresses along the transverse direction and the corresponding distribution of shear lag coefficients of UHPC slab,steel deck,steel bottom slab at middle of mid-span and central support areas are analyzed respectively.The research results show that:(1)the distribution of longitudinal normal stress and shear lag coefficient along the transverse direction of the sections of UHPC slab,steel deck,steel bottom slab with/without diaphragms are consistent;(2)the sections of UHPC plate,steel deck and steel bottom slab without diaphragm show negative shear lag effect in middle web,side web and cantilever web,while those with diaphragms show positive shear lag effect in middle web,side web and cantilever web.