单箱双室简支箱梁剪切变形剪力滞效应分析

Analysis on shear deformation and shear-lag effect of twin-cell box girders

基于各个翼板选取不同的最大剪切转角差为剪力滞广义位移,考虑剪力滞和剪切变形双重效应,应用能量变分原理推导出双室箱梁受竖向对称荷载时的截面控制微分方程组,采用降阶法并结合边界条件导出相应的闭合解,从力学和数学角度解释剪切变形对箱梁截面纵向应力无影响。以典型的单箱双室简支箱梁为例,利用数值方法和本文解析解方法,研究满跨均布力和跨中集中力荷载作用下,跨中截面剪力滞横向分布规律和高跨比对剪力滞效应的影响规律,研究结果表明:顶(底)板与腹板交汇处表现为正剪力滞效应,单室顶(底)板中心表现为负剪力滞效应;集中力、均布力下跨中截面测点剪力滞系数随高跨比的变化分别呈线性、曲线分布,顶(底)板与腹板交汇处测点剪力滞系数随高跨比的增大而增大,单室顶(底)板中心测点剪力滞系数随高跨比的增大而减小。

In view of each wing shoulder, different maximum shear angle differences are selected as the shear lag of generalized displacement. Taking the double effects of shear lag and shear deformation into consideration, the shear differential equations of twin-cell box qirder under the vertical symmetrical load are deduced on the basis of energy variational principle. The corresponding closed solutions are obtained by the method of reduced order and the boundary conditions. From the point of view of mechanics and mathematics, the shear deformation has no effect on the longitudinal stress of box girder. A typical example of the twin-cell box girders, using the numerical method and the analytic solution method in this paper to study shear lag transverse distribution law and effect of high span ratio on shear lag effect of measuring point in middle span under the uniform force and concentrated force.Research shows that： the junction of the top （ bottom） plates and the web plates are shown the positive shear lag effect, the middle of the top （bottom） of the single room are shown the negative shear lag effect. The variation of the shear lag coefficient with the height span ratio is the linear and the curve distribution under the concentrated force and uniform force, respectively the shear lag coefficient between the top （ bottom） plates and the web plates increase with the increase of high span ratio. The middle of the top （ bottom） of the single room decreases with the high span ratio increasing.