多跨系杆拱桥极限承载力影响因素

Influencing factors for ultimate bearing capacity of multi-span tied arch bridge

为求得多跨系杆拱桥的稳定系数和安全储备,建立了多跨系杆拱桥的空间有限元模型.通过特征值屈曲分析,得到了成桥状态各工况的稳定系数,并分析了横撑刚度和数量对稳定系数的影响.考虑材料非线性和几何非线性的极限承载力分析,得到了成桥状态的活载稳定系数和恒载稳定系数,并分析了风荷载、温度作用、荷载布置和初始缺陷对稳定系数的影响.分析结果表明,特征值屈曲分析可以提供结构极限承载力的合理估计,横撑刚度对结构稳定系数的影响较横撑数量的影响要大;极限承载力分析过程中主拱四分点部位和跨中部位首先进入塑性状态,静风荷载对结构稳定系数的影响较温度作用和初始缺陷的影响要大.

In order to obtain the stability coefficient and safety stock of multi-span tied arch bridge, a spatial finite element model for multi-span tied arch bridge was established. Through the buckling analysis on eigenvalue, the stability coefficients of the completed bridge state under various operating conditions were attained. In addition, the influence of bracing stiffness and bracing number on the stability coefficient was analyzed. Through the ultimate bearing capacity analysis with considering both material nonlinearity and geometric nonlinearity, the dead load and live load stability coefficients for completed bridge state were obtained. Moreover, the effect of wind load, temperature action, load arrangement and initial defect on the stability coefficient was analyzed. The analysis results show that the buckling analysis on eigenvalue can provide reasonable estimation for the structural ultimate capacity, and the bracing stiffness has a greater influence on the structural stability coefficient compared with the bracing number. In the analysis process of ultimate bearing capacity, the quarter points and mid-span of main arch firstly reach the plastic state. Furthermore, the static wind load has a greater effect on the structural stability coefficient compared with the temperature action and initial defect.