双薄壁高墩曲线多跨连续刚构桥自振特性分析

Analysis to Free Vibrations of Multi-span Continuous Rigid Frame Curved Bridge with Double Thin-walled High Pier

为确定双薄壁高墩曲线多跨连续刚构桥的自振特性,以某双薄壁高墩曲线五跨连续刚构桥为实例,应用ANSYS有限元软件中的Solid 65实体单元和Beam 188梁单元建立该桥空间有限元计算模型,同时利用Midas/Civil建立大桥空间梁单元有限元模型,探讨不同软件、不同单元类型以及预应力张拉对双薄壁高墩曲线多跨连续刚构桥自振频率的影响,分析曲线桥梁结构的平曲线半径对双薄壁高墩曲线连续刚构桥的自振特性的影响,最后按照桥墩等线刚度的原则分析墩高对双薄壁高墩曲线连续刚构桥的自振特性的影响.计算结果表明:曲线连续刚构桥第1阶振动模态一般为纵飘;曲线桥梁结构动力特性及其力学行为的分析,建议选用可考虑翘曲的Beam 188梁单元模型;对于高等级公路中的曲线半径较大的双薄壁高墩曲线连续刚构桥,曲率半径对桥梁的自振特性影响很小;在保持墩线刚度不变的前提下,结构的自振频率随着墩高的增大而减小,可以通过优化墩的纵桥向厚度或双薄壁墩间距改善结构的整体刚度.

The free vibration feature of a five-span continuous rigid frame curved bridge with double thinwalled high pier was analyzed to understand free vibration feature of continuous rigid frame curved bridge with double thin-walled high pier. Solid 65 and Beam 188 element of analytical software ANSYS was used to build the bridge structural spatial model. Midas / Civil software was used to build the model of spatial beam element. By analyzing these models,the effect of the different software and element type and prestressed tension to structural vibration feature,the influence of curvature radius and pier height with principle of equal line stiffness was analyzed. The results indicated that the first-order vibration mode was longitudinal drift in general. Considering the structural feature and the rotational freedom,it was suggested that the dynamic properties and the mechanical behavior of the curvature bridge were analyzed by using Beam 188 element. The impact of curvature radius＇ on continuous rigid frame curved bridge with a large radius of curvature and double thin-walled high pier in the highway was not significant. Under the principle condition of equal line stiffness,the natural frequencies of the structure decreased with pier height＇s increase. The structural stiffness could be improved by changing the piers＇ longitudinal thickness or double thin-wall pier spacing.