中小跨径桥梁抗震的概念设计与构造措施

为改善中小跨径桥梁的抗震性能,总结了青海玛多地震、汶川地震等震害,阐述了合理的抗震概念设计以及合适的构造措施,基于“多道设防,分级耗能”“一可三易(损伤部位及损伤程度可控、损伤部位或构件易检、损伤部位或构件易修、损坏部位或构件易换)”的桥梁抗震理念,提出将支座作为“保险丝式单元”的桥梁抗震概念设计。针对中小跨径简支梁桥易发生落梁震害,提出了适当增加盖梁宽度和横向设置双层挡块的抗震构造设计,建议在进行桥梁抗震设计和抗震评价时,统一抗震构造措施,不应再按照烈度(或基本地震动参数)划分桥梁抗震构造设计。从结构基本周期和频谱成分的角度,总结并分析了玛多地震中结构相似的相邻桥梁发生不同震害的原因。研究成果可为同类工程的抗震设计与评价提供参考。

Conceptual Design and Construction Measures of Small-to-medium Span Bridge Seismic

To improve the seismic performance of small-to-medium span bridges, the reasonable seismic conceptual design and appropriate structural measures were expounded by summarizing the seismic damage of Qinghai Maduo earthquake and Wenchuan earthquake. Based on the bridge seismic concept of “multiple defenses, graded energy consumption” and “one can and three easy(the damaged part and degree of damage can be controlled, the damaged part or member can be easily inspected, repaired, and replaced)”, the seismic conceptual design of bridge with bearing as “fuse-type unit” was suggested. Considering that the small-to-medium span simply supported bridges were prone to damage caused by falling beams, the seismic structural design methods of appropriately increasing the width of bent cap and setting double-layer block transversely were proposed. It was recommended that the seismic design and seismic evaluation of the bridge should be unified with seismic structural measures and the seismic design of bridge should not be divided according to intensity or basic ground motion prarameter. The reasons for the different earthquake damages of adjacent bridges with similar structures in Maduo earthquake were summarized and analyzed from the perspective of the basic period of the structure and the frequency spectrum components. The research findings can provide reference for seismic design and evaluation of similar engineering.