变截面箱梁桥悬臂施工过程剪力滞效应

为了研究剪力滞效应对变截面箱梁桥悬臂施工过程的影响，以某新建(48+80+48)m变截面预应力混凝土连续箱梁桥为工程背景，通过理论分析、数值模拟和现场试验的手段，对变截面箱梁桥悬臂施工过程中的剪力滞效应进行了研究。研究发现：变截面箱梁桥在施工阶段的自重荷载作用下，翼板出现负剪力滞效应，剪力滞效应在固定端最小，且随离固定端距离的增大而增大。在整个施工阶段，0号块截面和1号块截面的剪力滞效应变化规律基本一致，均在箱梁顶板位置出现负剪力滞，箱梁底板位置出现正剪力滞，随着施工的进行，剪力滞效应逐渐减小。梁体的合龙对底板的剪力滞效应影响较明显，其中0号块截面和1号块截面的底板剪力滞出现了由正剪力滞变成负剪力滞的现象。随着施工的进行，0号块截面顶板和腹板交接处的剪力滞系数逐渐增大，在底板和腹板交接处剪力滞系数逐渐减小，1号块梁端截面顶板和腹板交接处、底板和腹板交接处剪力滞系数逐渐减小。

Shear Lag Effect of variable section box girder

In order to study the influence of shear lag effect on the construction process of variable section box girder, with a new-built (48+80+48)m variable section prestressed concrete continuous box girder as the engineering background. By means of the theoretical analysis, numerical simulation and field test, the shear lag effect of the construction process of variable section box girder were studied. The results show that the wing plate has a negative shear lag effect, when the variable section box girder is under the dead weight load of the construction stage. And the shear lag effect is the smallest at the fixed end, with the increase of the distance from the fixed end, the shear lag effect is more obvious. In the whole construction stage, the shear lag effect of block-0 and block-1 are basically consistent. Negative shear lag effect appears on the top of box girder, positive shear lag effect appears on the bottom of box girder, with the construction in progress, the shear lag effect is gradually decreased. The closure of the girder body has an obvious effect on the shear lag effect of the bottom plate, The shear lag effect of block-0 and block-1 has changed from positive shear lag effect to negative. As the construction proceeds, The shear lag coefficient at the junction of the roof and the web of block-0 is gradually increased, and gradually decreases at the junction of the floor and the web. The shear lag coefficients are gradually decreases for both at the junction of the roof and at the junction of the floor of block-1.