大跨度铁路钢桁梁柔性拱桥的弹性稳定性

Static elastic stability of long-span railway steel truss flexible arch bridge

为研究大跨度铁路钢桁梁柔性拱桥在施工阶段和运营期的稳定性,应用静力弹性稳定和有限元方法分析某双主跨钢桁梁拱桥不同时期的力学行为,并获得相应的失稳模态。研究结果表明:结构的线弹性稳定系数在其建造中经历了一个由逐渐增加再到减小直至平稳阶段的变化过程,且施工阶段和运营期的稳定安全系数都较高;施工阶段桥梁结构失稳形式多表现为单根或少量杆件失稳,而运营期则均表现为拱肋的整体失稳;当列车荷载为主跨满载时,桥梁的稳定安全系数最低;若将杆件应力达到屈服时的系数作为承载力系数,则最不利杆件的屈服系数与结构整体的稳定系数相差较大。

In order to study the linear elastic stability of long-span railway steel truss flexible arch continuous girder bridge at construction and operation,the mechanical behavior of a double main span of steel truss arch bridge in different stages is analyzed by using the static elastic stability and finite element method,and the corresponding instability modes are obtained.The results show that the linear elastic stability coefficient of the steel truss girder flexible arch bridge under goes a gradual process of the increase and then decrease to the stationary phase.The stability safety coefficients during construction and operation are both high.In the construction stage,the instability forms of bridge structures are mostly the instability of single or a few bars,while the operation stage is characterized by the overall instability of the arch rib.When the main span is full loaded,the stability and safety factor of the bridge drops to the lowest.If the coefficient of the stress of the bar to yield is taken as the coefficient of bearing capacity,the yield coefficient of the most unfavorable members is quite different from that of the whole structure.