波形腹板钢箱组合梁竖向弯曲振动特性

Vertical Bending Vibration Characteristics of Box Composite Cirder with Corrugated Steel Webs

综合考虑剪切变形、剪滞翘曲应力自平衡、转动惯量和腹板褶皱效应的影响,对组合箱梁上、下翼板和悬臂板设立2个不同的剪滞转角差函数,基于能量变分法和Hamilton原理建立该类结构的弹性控制微分方程和自然边界条件,获得相应广义位移的闭合解。通过模型实测值和ANSYS空间有限元值验证了该闭合解的可靠性,并分析了宽跨比对组合箱梁竖向弯曲振动特性的影响。研究结果表明:与剪力滞效应相比,剪切变形对组合箱梁抗弯刚度的影响更大,第4阶自振频率差值达到27.623%;结构跨中横截面上各点动应力幅值的分布特点与其静力分析结果类似,荷载作用频率对组合箱梁的动剪力滞系数的影响小于3.52%;剪力滞效应对简支组合箱梁翼板动应力幅值的影响随宽跨比的增大而变大,翘曲应力自平衡的影响亦随之增大;翘曲应力自平衡对结构自振频率的贡献值小于5%,但对翼板动应力幅值的影响可达9.4%以上。

Considering the effects of shear deformation,shear lag warping stress self-equilibrium,moment of inertia and web accordion effect,two different shear lag angle difference functions are set up for the upper and lower wing plates and cantilever plates of composite box girder.The elastic governing differential equations are established based on the energy variational method,Hamilton principle,and natural boundary conditions of the structure,and the closed solutions of the corresponding generalized displacements are obtained.The reliability of the closed form solution is verified by the measured values of the model and the finite element analysis from ANSYS software.Finally,the influence of width span ratio on the vertical bending vibration characteristics of composite box girder is analyzed.The results show that compared with the shear lag effect,the shear deformation has a greater influence on the flexural stiffness of composite box girder,and the difference of the fourth natural frequency is 27.623%.The distribution characteristics of the dynamic stress amplitude at each point of the cross section in the middle span of the structure are similar to the static analysis results,and the influence of the load frequency on the dynamic shear lag coefficient of composite box girder is less than 3.52%.Moreover,the influence of shear lag effect on the dynamic stress amplitude of simply supported composite box girder flange increases with the augment of width span ratio,and the influence of warping stress self-equilibrium also increases.In addition,the contribution of warping stress self-equilibrium to the natural frequency of the structure is less than 5%,but the influence on the dynamic stress amplitude of flange can reach more than 9.4%.