钢管混凝土单圆管拱结构罕遇地震作用动台阵试验研究

SHAKING TABLES TESTING OF CONCRETE FILLED STEEL TUBULAR SINGLE ARCH RIB MODEL UNDER THE EXCITATION OF
RARE EARTHQUAKES

  • 摘要: 对缩尺比例为1∶10的钢管混凝土单圆管拱结构模型进行了罕遇地震作用下振动台台阵试验研究。试验结果表明:罕遇地震作用下该模型拱结构各主要截面的应变均超过了材料的弹性极限应变,结构进入了非线性弹塑性阶段;不过,由于套箍作用,模型拱结构的刚度并没有显著的下降,模型拱钢管表面也未出现开裂和破坏现象,钢管混凝土拱结构表现出了良好的抗震性能。试验还表明:输入的地震波反应谱不同,结构的地震响应也不同,其放大效应与输入波形反应谱的起始卓越频率、范围及结构特性相关,最大响应则与反应谱峰值大小相关;拱结构横桥向激励产生的响应一般要远大于纵桥向的,尤以拱顶处最为明显;相对于拱结构静力分析时一般是考虑截面的上、下缘应变来说,地震作用下左、右缘应变更大、更为不利,尤以拱脚截面处最显著。

     

    Abstract: In order to understand the seismic behavior of concrete filled steel tubular (CFST) arch ribs under the rare earthquakes excitation of ELcentro wave and Hanshin wave, a CFST model of scaled 1∶10 was constructed on the unique Earthquake Simulator of Triple Shaking Tables Array at Fuzhou University. The testing results indicate that the CFST arch rib structure has entered into the nonlinear elastic-plastic phase since the strains of the steel tube and core concrete in the mainly sections of an arch rib are far larger than their limit elastic stains. However, the stiffness and natural frequencies of the arch rib model do not have significant decrease because of the hooping effect on the core concrete subjected by the steel tube. Moreover, there are no distinct cracks or damage on the surface of the steel tube, which reveals that the CFST arch rib structure has a favorable seismic performance. The testing results also show that the different earthquake response spectrums will relatively induce the varying seismic performance, and the magnifications of response are related to the waves’ predominant frequencies, ranges and peak vales as well as the model’s dynamic behavior. Furthermore, the responses of accelerations, displacements, and strains under the excitation in the Y-transverse direction are generally larger than that in the X-longitudinal direction, especially at the arch crown. Otherwise, compared to the strains in the top-bottom edge at the cross-section of springs, the strains in right-left edge are larger and more disadvantageous, which need to be considered.

     

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