Earthquake Response Behavior and Seismic Design Method for R/C Structures Based on Influence of Underground Structure

地面和由基础和桩组成的地下结构对钢筋混凝土上部结构在地震作用下的整体响应行为的影响几乎没有明确的研究。本研究的目的是明确考虑地面和地下结构动力特性的R/C桥墩的地震反应行为，为建立合理的R/C结构抗震设计方法做出贡献。假设地面和地下结构的动力特性分别为摇摆弹簧和摇摆弹簧，对R/C桥整个桥墩进行了动力响应分析。恢复力模型采用Hardin-Drnevich模型，R/C墩采用双线性刚度退化模型。通过分析，得出以下结论：(1)当地基较软时，地下结构引起的桥墩位移较大，但桥墩顶部的响应加速度较小。(2)采用实际现场试验得到的桥墩屈服位移进行分析时，摇晃引起的桥墩位移占主导地位。

The influence of ground and an underground structure consisting of a footing and piles on whole response behavior of a reinforced concrete(R/C) superstructure under earthquakes has hardly been clarified. Theobjectives of this study are to make clear earthquake response behavior of R/C bridge piers considering dynamic properties of ground and underground structures and to contribute to the establishment of a reasonable seismic design method for R/C structures.Assuming the dynamic properties of the ground and the underground structure to be a sway and a rocking springs, dynamic response analysis of whole R/C bridge piers was carried out. As for the restoring-forcemodels, Hardin-Drnevich model was used for each spring and bi-linear degrading stiffiness model was used for the R/C pier.From the analyses, it is concluded as follows;(1)When the ground is soft, the displacement of the pier due to the underground structure becomes large though the response acceleration at the top of the pier becomes small.(2)When the yield displacement of the pier obtained from actual field tests is used for the analysis, the displacement of the pier due to the rocking is dominant.