钢箱梁高度对桥梁颤振稳定性影响数值计算研究

Numerical Study on Influence of Steel Box Girder Height on Bridge Flutter Stability

为设计合适的梁高,在达到结构受力的条件下以较少的用钢量满足桥梁的气动稳定性.本文首次综合考虑了箱梁气动外形变化和刚度变化,运用全桥多模态颤振分析方法计算分析箱梁高度变化对颤振临界风速的影响.并通过颤振导数变化规律,颤振发生时各振型的能量分布来说明优化机理.计算表明:在箱梁宽度相同,风嘴角度相同的情况下,随着箱梁高度的增加,桥梁竖弯频率基本保持不变,扭转频率增加,扭转刚度增加.同时箱梁流线型变差,气动外形变差,颤振发生时竖弯和扭转振型参与程度发生变化.在一定的梁高范围内,桥梁的颤振稳定性没有随梁高线性变化,存在一个最优梁高,使得桥梁颤振临界风速最大.

In order to find a suitable beam height to meet the aerodynamic stability on the premise of saving steel as much as possible. In this paper, the effects of box girder aerodynamic shape changes and stiffness changes were comprehensively considered, and the full bridge multi-modal flutter analysis method was used to calculate and analyze the influence of box girder height changes on flutter critical wind speed. The optimization mechanism was illustrated by the variation law of flutter derivatives and the energy distribution of each mode when flutter occurs. The calculation shows that with the same width of the box girder and the same angle of the air nozzle, the vertical bending frequency of the bridge basically remains unchanged, the torsional frequency increases and the torsional rigidity increases with the increase of the box girder height. Meanwhile, the streamline of box girder becomes worse and the aerodynamic shape becomes worse. Under the action of two opposite factors, the flutter stability of the bridge does not change linearly with the beam height, and there is an optimal beam height, which makes the critical flutter wind speed of the bridge maximum.