桥梁横向抗倾覆概念设计

Conceptual Design for Lateral Anti-overturning of Bridges

相关技术规范对桥梁横向稳定明确了支座脱压和抗倾覆稳定系数的计算方法,但对失效支座反力的计算存在疑问,两者的工况是不同的。支座脱压计算属于正常使用范畴,应考虑所有可能出现的作用;抗倾覆稳定系数计算支座已脱空,间接作用在失效支座不产生反力,且其产生的反力是平衡力系,对桥梁不起倾覆和稳定的作用,因此不计间接作用。关于稳定和失稳力矩的计算公式,隐含倾覆轴,有效支座连线与倾覆侧桥边缘线形成的区域是抗倾覆概念设计的关键,可定性判断倾覆最不利车道和最不利支座。对于独柱墩桥梁抗倾覆的加固,主要有新增支座、改支座支承为墩梁固结、左右幅箱梁连接、增设横向限位和抗拉拔装置方案等,其中新增支座是最常用、最有效的方案。

In this article,clear calculation methods for the bearing uplift and anti-overturning stability coefficients for lateral stability of bridges have been provided.But there are concerns about the calculation of the reaction force of failed bearings as the working conditions are different.The calculation for bearing uplift belongs to the normal usage and should consider all possible effects.The calculation of the anti-overturning stability coefficient assumes that the bearing has already been lifted,and indirect effects on the failed bearing do not produce reaction forces.The reaction forces produced form a balanced force system that does not cause the anti-overturning and stability of the bridge,so there are no indirect effects.Regarding the calculation formulas for stability and instability moments,the overturning axis is implicitly involved.The area formed by the effective bearing connection line and the edge line of the overturning side bridge is the key concept of the anti-overturning design,which can qualitatively determine the most unfavorable lane and the most unfavorable bearing for overturning.For anti-overturning reinforcement of single-column pier bridges,the main solutions include adding new bearings,changing the bearing support to the pier beam,connecting the left and right box beams,adding transverse limit and anti-pull-out devices.Among these,adding new bearings is the most commonly used and effective one.