墩高对应用LNR支座简支梁桥抗震性能的影响

Effects of Pier Height on Seismic Performance of Simply-supported Girder Bridge with LNR Bearings

LNR水平力分散型橡胶支座以低剪切刚度适应大剪切位移,实现桥梁下构水平力分散,协调墩台抵抗水平力。为研究LNR支座在不同墩高桥梁上的抗震性能,以板式橡胶支座为参照,以标准跨径为40 m的多跨公路简支梁桥为对象,在不同墩高范围对采用2种支座的桥梁进行动力分析,并对比结构动力响应,评估LNR支座的抗震性能。结果表明,相对于板式橡胶支座,LNR支座能延长结构的自振周期,降低桥梁地震内力。随着墩高增加,LNR支座在纵向地震下的优势显著下降,在横向地震下的优势下降不明显,采用LNR支座的桥梁内力能力需求比也逐渐下降。综合考虑,高墩桥梁采用LNR支座的优势并不明显。

Laminated nature rubber bearings(LNR bearings)are designed to accommodate large shear displacement with low shear stiffness,enabling the dispersion of horizontal forces in bridge substructures and coordinating the resistance of piers to horizontal forces.To investigate the seismic performance of LNR bearings on bridges with different pier heights,a dynamic analysis of two types of bearings was conducted on multi-span highway simply-supported girder bridges with a standard span of 40 m,using plate rubber bearings as reference.In addition,the structural dynamic response was compared to evaluate the seismic performance of LNR bearings.The findings indicate that compared to plate rubber bearings,LNR bearings can extend the natural vibration periods of the structure and reduce seismic internal forces in the bridge.As the pier height increases,the advantage of LNR bearings under longitudinal earthquakes diminishes significantly while remaining unaffected by transverse earthquakes.Additionally,there is a gradual decrease in the ratio between capacity and demand of internal force for bridges utilizing LNR bearings.Taking these factors into consideration collectively,it can be concluded that the advantages of LNR bearings for high-pier bridges are not particularly pronounced.