超宽桥的地震反应分析及优化设计

Seismic response analysis and optimization design of extra wide bridge

随着超宽桥在城市建设中的广泛应用,超宽桥的抗震性能研究显得十分重要。文章首先对超宽桥抗震分析建模方法的适用性进行对比分析,并根据全桥动力性能特点对超宽桥进行了界定;然后,根据对普通宽度桥梁和超宽桥的地震反应特点进行研究,指出了超宽桥在地震作用下的受力薄弱环节;最后,通过改变桥墩布置形式、墩间横向连接以及横向支座约束方式等措施对超宽桥结构进行优化分析,提出了提升超宽桥抗震性能的设计对策。研究结果表明:从抗震性能角度,可将宽跨比大于等于1的桥梁界定为超宽桥;相对于梁单元模型,采用梁格模型能够较好地模拟超宽桥刚度分布的空间效应;由于超宽桥在横向地震作用下支座的反力和剪力较大且分布严重不均匀,容易出现横向倾覆的危险,应将横桥向作为其抗震设计的重点;为提高超宽桥抗震性能,宜采用多柱式桥墩,并适量增加横向约束支座和墩间横向连接以增加桥梁的横向刚度,使得桥墩内力的分布更为均匀、合理。

With the wide application of extra wide bridge in urban construction, its seismic performance research is very important. The applicability of extra wide bridge seismic analysis modeling method is analyzed firstly in this paper, and the extra wide bridge is defined according to the dynamic performance of the whole bridge. Then, ac- cording to the seismic response characteristics of average width bridge and extra wide bridge, the weak link of extra wide bridge under seismic action is pointed out; finally, the design countermeasures of extra wide bridge are pres- ented to improve the seismic performance by optimization analysis of bridge through changing the arrangement of piers, transverse connections between piers and transverse bearing constraints. The results show that： such bridge for which the width span ratio is seismic performance. The grillag greater than or equal to 1 can be defined as an extra wide bridge from the angle of e model can simulate the spatial effect of the distribution of stiffness for the extra wide bridge better than the spatial beam model. The bearing reaction force and the shear force of extra wide bridge under horizontal seismic action are large and distribute seriously unevenly which are prone to cause lateral overtur- ning, so the transverse direction of bridge should be seen as the focus of the seismic design. In order to improve the seismic performance of the extra wide bridge, appropriate using multi-column piers, moderate increasing lateral constraints between bearings and transverse connections and between piers to increase the lateral stiffness of bridge will make the distribution of the internal force of piers uniform and reasonable.