钢管混凝土单圆管拱模型重力失真影响振动台试验研究

为了研究重力失真对振动台试验相似模型地震响应的影响，基于人工质量的混合模型相似理论，以缩尺比为1:10的钢管混凝土单圆管拱结构为试验模型，通过设置5种不同人工质量为重力失真度参数，采用5种不同时间压缩比的地震波及人工波，进行了纵向、横向地震模拟振动台试验。试验结果表明:重力失真对拱结构模型第一阶频率相似的影响显著，重力失真度越大，模型第一阶频率相似系数试验值和理论值之间的误差也越大；输入波的频率比较小时，重力失真度越小的模型加速度响应越大，加速度峰值时间越延后；重力失真度和输入波的频率比对模型横向（Y向）加速度响应的影响要大于纵向（X向）的影响；通过调整模型配重及输入波的频率比，可减小模型的重力失真对加速度响应的影响。

GRAVITY DISTORTION EFFECT ON SHAKE TABLE TESTS OF CONCRETE FILLED STEEL TUBULAR SINGLE ARCH RIBS

To study the effects of gravity distortion on the seismic responses of concrete filled steel tubular (CFST) bridges, a shake table test was conducted for 1/10-scale CFST single arch ribs based on the theory of hybrid model of artificial mass. Five artificial masses were set up to obtain different degrees of gravity distortion. Several earthquake waves and artificial waves with five time-compressive similarity coefficients were input in both the longitudinal and transverse directions in the test. The test results indicate that the gravity distortion has great effects on the first natural vibration frequency of the model. The greater the gravity distortion, the greater the error between the experimental and theoretical values of the first frequency similarity coefficient of the specimen will be. When the earthquake waves are adopted with a small frequency ratio, the gravity distortion of the model is smaller, the acceleration response is larger, and the time of the peak acceleration is later. The effects of the gravity distortion and frequency ratio of the input waves on the acceleration response in the transverse direction are more significant than those in the longitudinal direction. The effects of the gravity distortion on the acceleration response can be reduced by adjusting the complementary artificial mass of the model and the frequency ratio of the input waves.