曲率半径对曲线箱梁桥模态及振型方向因子的影响

Influences of Span Ratio on Modals and Mode Direction Factors of Curved Box-girder Bridges

按能量比重将曲线箱梁桥的振型分解为竖向弯曲、扭转、横向弯曲和纵向移动四个振型方向因子。以曲率半径为参数建立了4个两跨曲线箱梁桥模型,分析了其模态特性及各振型方向因子随曲率半径的变化规律。认为随着曲率半径的减小,曲线桥刚度的增加比质量的增加要慢,必须充分考虑竖向弯曲振型,扭转振型方向因子随着曲率半径的减小逐渐减小,纵向移动振型方向因子高峰值出现在较高阶次的模态中,高阶模态对其抗震性能的影响非常重要,在抗震设计时必须充分考虑足够多的高阶模态的影响。

The vibration mode of curved box-girder bridge was decomposed into 4 mode direction factors by energy ratios. 4 two-span curved box-girder bridge models were built taking span ratio as parameter. The modal characteristics and the mode direction factors were analyzed alone with span ratio varying. It is advised that the rigidity increases more slowly than mass for curved box-girder bridge,vertical bending mode must be taken account,torsional mode factor decreases with the decreasing of span ratio,the summit of longitudinal movement direction mode factor appears on higher modal orders. high order modals must be considered when designing.