超大跨度公铁两用悬索桥活载刚度研究

Study on Stiffness of Super⁃long Span Rail⁃cum⁃Road Suspension Bridge Under Live Load

为提高超大跨度公铁两用悬索桥在活载作用下的刚度,对多个影响参数开展了考虑几何非线性的敏感性分析。以高精度的悬链线理论为基础,计算并确定超大跨度公铁两用悬索桥的成桥线形、主缆及吊杆的无应力长度、主缆的分点坐标等数据,建立并更新桥梁的空间有限元模型。以活载作用下主跨最大挠度、梁端转角及梁端纵向变形为评价指标,对主跨1560 m结构方案进行活载几何非线性效应多参数影响分析。结果表明:超大跨度公铁两用悬索桥活载几何非线性效应显著,简化的线性方法会放大活载效应,设计不经济,应采用高精度悬链线理论计算活载效应;矢跨比、主塔刚度、边缆跨度及边跨加劲梁长度对悬索桥刚度均有不同程度的影响,在设计中应根据活载效应进行结构优化。

In order to improve the stiffness of super-long span highway railway suspension bridge under live load,the sensitivity analysis considering geometric nonlinearity was carried out for several influencing parameters.Based on the high-precision catenary theory,the finished alignment,the unstressed length of main cable and suspender,and the point coordinates of main cable of the super-long span rail-cum-road suspension bridge were calculated and determined,and the spatial finite element model of the bridge was established and updated.Taking the maximum deflection of the main span,the girder end rotation angle and the longitudinal deformation of the girder end under live load as the evaluation indexes,the multi-parameter influence analysis of the live load geometric nonlinear effect of the main span of 1560 m was carried out.The results show that the live load geometric nonlinear effect of super-long span rail-cum-road suspension bridge is significant,the simplified linear method will amplify the live load effect,and the design is not economical,so the high-precision catenary theory should be used to calculate the live load effect.The rise span ratio,the stiffness of main tower,the span of side cable and the length of side span stiffening girder have different degrees of influence on the stiffness of suspension bridge,the structure should be optimized according to the live load effect in the design.