墩底局部加密纵筋铁路重力式桥墩的试验研究

Experimental Research on the Railway Gravity Bridge Piers with Reinforced Longitudinal Reinforcement at Pier Bottom

研究目的:为提高低配筋率铁路重力式桥墩的抗震性能,提出一种墩底局部加密纵向钢筋的设计方法。制作5个不同加密纵筋高度的模型桥墩,通过拟静力试验对比分析仅提高墩身底部配筋率桥墩的抗震性能。研究结论:(1)确定了加密纵筋高度的计算方法,推导出了加密纵筋高度的计算公式;(2)仅在墩底加密纵向钢筋可有效提高桥墩的水平承载能力和耗能能力;(3)仅在墩底加密纵向钢筋桥墩的承载能力和耗能能力基本能达到与加密处配筋率相同桥墩的承载能力和耗能能力,且刚度基本不会降低;(4)拟静力试验结果验证了墩底加密纵筋提高桥墩抗震性能的可行性以及纵筋加密高度计算方法的合理性;(5)本研究成果可应用于需要提高抗震性能桥墩的设计中。

Research purposes: In order to improve the seismic performance of railway gravity bridge piers with low longitudinal reinforcement ratio, the design method is proposed to locally increase the amount of longitudinal reinforcement at the bottom of the pier. Five model piers with different reinforcement height are made, and the seismic performance of the piers with only increased the longitudinal reinforcement ratio at the bottom of the pier is compared and analyzed through the pseudo-static test.Research conclusions:(1)The calculation method of the height of the longitudinal reinforcement is determined and the calculation formula of the height of the longitudinal reinforcement is deduced.(2)The horizontal bearing capacity and energy dissipation capacity of the pier can be effectively improved by increasing longitudinal reinforcement ratio at the bottom of the pier.(3)The bearing capacity and energy dissipation capacity of the pier with the supplementary longitudinal bars at the bottom are basically the same as that of the pier with the same longitudinal reinforcement ratio at the supplementary place, and the stiffness will not be reduced basically.(4)The results of the pseudo-static test verify the feasibility of enhancing the seismic performance of the pier by increasing the number of longitudinal bars on the bottom of the pier and the rationality of the calculation method of the height of the increased longitudinal reinforcement.(5)The research results can be applied to the design of piers which need to improve the seismic performance.