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基于有限元方法,以ANSYS为平台建立了南阳淅川段习营下承式钢管混凝土拱桥三维有限元模型,采用子空间迭代法求解桥梁的自振频率和振型,并结合桥面振动实测频率,验证了桥梁模型的准确性.计算结果显示,桥梁1阶竖向振动频率的实测值与理论值接近,模型精度较高.拱桥第1阶振型为拱肋横向弯曲,第2、3阶振型均为桥面系竖向弯曲.低阶振型主要以拱肋的横向振动或桥面系的竖向弯曲为主,说明该桥拱肋横向刚度明显小于竖向刚度,桥面系横向刚度远大于竖向刚度,体现了下承式钢管混凝土拱桥的动力性能特征.计算结果为结构性能评估与抗震设计提供了依据.
Based on the finite element method and ANSYS platform, a three-dimensional finite element model of Xiying under-standing CFST arch bridge in Xichuan section of Nanyang was established. The subspace iterative method was used to solve the natural frequency and vibration mode of the bridge. Combined with the measured frequency of bridge deck vibration, The results show that the measured value of vertical vibration frequency of the first order bridge is close to the theoretical value and the accuracy of the model is high.The first order mode of the arch bridge is transverse bending of the arch rib and the second and third order vibration Type are vertical bending of bridge deck.Low-order vibration mode is mainly transverse vibration of arch rib or vertical bending of deck system, which shows that transverse rigidity of arch bridge rib is obviously less than vertical stiffness and bridge deck transverse rigidity Which is much larger than the vertical stiffness and reflects the dynamic performance characteristics of the CFST arch bridge.The results provide the basis for structural performance evaluation and seismic design.