厚软场地上大跨径桥梁设计反应谱研究

大跨径桥梁塔高、跨径大、自振周期长,深厚、软弱场地的长周期地震动对桥体结构影响较大。我国《公路工程抗震设计规范(JT J004-89)》也只适用主跨不超过150 m的梁桥和拱桥,国内长期以来没有一个适用于大跨径桥梁的抗震设计规范或指南。本文结合大跨径桥梁工程实例,根据场地土层静、动力性能参数的原位测试和动三轴试验结果,进行厚软场地土层地震反应分析,研究厚软场地的地震动效应,讨论了不同地震动强度时厚软场地的设计反应谱特征,分析了现行规范设计反应谱应用的局限性,成果对相关工程有重要指导意义,对大跨径桥梁抗震设计规范的制定也有借鉴作用。

Study on Response Spectra for Design of Large Span Bridge on Ground with Thick and Soft Soil Layers

Large span bridges have high towers and large spans with long natural-vibration cycle,and long vibration cycles ofground with thick and soft soil layers have significant effect on the bridge structures.The "Specifications of Earthquake Re-sistant Design for Highway Engineering of China(JTJ004-89)" can also be applied to girder bridges and arch bridges with amain span below 150 m,yet,there has been no anti-seismic design specification or guideline in China applicable to large spanbridges.In this paper,the author has performed seismic response analysis for ground with thick and soft soil layer in conjunc-tion with examples of large span bridge projects on the basis of the results of static and dynamic performance parameter in-situtests of ground soils and dynamic triaxial test,studied the seismological effect of ground with thick and soft soil layers,dis-cussed the design response spectrum characteristics of ground with thick and soft soil layer at different seismic intensities,andanalyzed the limit of current specification of design response spectrum in actual applications.The results have important guid-ing significance to relevant projects,and can also be used in the promulgation of aseismic design code for large-span bridges.