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该文以地震下、修复中以及修复后遭遇地震的钢筋混凝土框架的动力特性为研究目的,进行了框架模型的初次振动台试验、震损后修复和再次振动台试验。试验对象为相似比1/4的双跨8层混凝土框架。在初次振动台试验中,框架模型经过31个工况地震波和5次白噪声的输入,结构破坏明显。其后,对框架损伤区域的裂缝进行压力注胶修补,并通过地脉动法和撞击荷载法监测修复过程中结构动力特性的变化。修复后,再次进行工况相同的振动台试验。试验结果表明:框架模型的频率随输入地震动幅值的加大而明显降低,阻尼比则随之明显增大;修复过程中,结构的频率和阻尼比逐步恢复,第一自振频率达到甚至超过模型的原有水平;修复后的再次振动台试验中,模型的频率降幅及阻尼比的增幅均低于初次振动台试验。结合两次试验中结构的变形幅度可知,结构动力特性与其抗震性能有密切的关系。通过动力特性指标的变化,能有效反映框架结构在震损及修复中的抗震性能。
In this paper, the dynamic characteristics of reinforced concrete frame under earthquake, during restoration and after earthquake are studied. The initial shaking table test, post-earthquake damage repair table and re-shaking table test are carried out. The test object is a similar ratio of 1/4 double span 8-story concrete frame. In the initial shaking table test, the frame model is subjected to 31 conditions of seismic waves and 5 times of white noise input, the structural damage is obvious. Subsequently, the cracks in the damaged area of the frame were repaired by pressure injection, and the dynamic characteristics of structures during the repairing process were monitored by ground pulsation method and impact load method. After the repair, the same shaking table test again. The experimental results show that the frequency of the frame model decreases obviously with the increase of input seismic amplitude, and the damping ratio increases obviously. During the restoration process, the frequency and damping ratio of the structure gradually recover, and the first natural frequency reaches or even increases Which exceeds the original level of the model. In the re-shaker test, the amplitude of the model and the increase of the damping ratio are lower than those of the initial shaker test. According to the deformation amplitude of two structures, the dynamic characteristics of the structure are closely related to its seismic performance. Through the change of dynamic characteristic index, the seismic performance of frame structure in earthquake damage and repair can be effectively reflected.