水平及竖向地震作用下多高层RC框架混合试验

Hybrid test of multi-story RC frames under combined excitation of horizontal and vertical earthquakes

摘要:

以往混合试验方法大多只考虑水平地震作用,为进一步拓展混合试验方法的应用,本文提出一种水平及竖向地震共同作用下多高层钢筋混凝土(RC)框架混合试验方法。该方法对框架结构计算模型和子结构边界条件进行合理简化,框架结构水平振动和竖向振动分别采用串联质点系模型和串并联多质点系模型进行模拟。在此方法基础上开发出一套完整的混合试验程序,该程序利用Matlab编写运动方程求解模块,采用OpenSees模拟数值子结构,并结合加载设备HNU-MUST开发出混合试验控制程序。为验证本方法和程序,设计并制作一根足尺RC框架柱作为试验子结构,并以一榀七层三跨RC框架作为整体结构进行混合试验,试验的顺利进行和良好稳定的试验控制效果验证了本方法的可行性与有效性。试验结果表明:在水平和竖向地震共同作用下RC框架柱轴力会发生剧烈变化,该轴力变化会使试件的受力状态和破坏形态变得较为复杂,同时可能会降低试件的强度和延性,并最终导致滞回曲线呈现不对称性和一定的“捏缩”现象。

Abstract:

Most existing hybrid test methods for building structures only consider the horizontal earthquake excitation. For further application, a hybrid test method of multi-story reinforced concrete (RC) frames under the combined excitation of horizontal and vertical earthquakes was developed. In this method, the frame structure calculation model and substructure boundary conditions were reasonably simplified. The horizontal and vertical vibrations of frame structure were simulated by series mass system model and series-parallel multi-mass system model respectively. Then, a complete set of hybrid test program was developed based on the proposed method. In the program, Matlab was adopted to form a motion equation solving module, OpenSees was used to simulate the numerical substructure, and loading equipment HNU-MUST was combined to develop a hybrid test control program. For verifying the proposed method and program, a full-scale RC frame column was designed and fabricated as the test substructure, and a seven-story three-bay RC frame was used as the overall structure for hybrid test. The smooth progress of the test and the stable test control effect verified the feasibility and effectiveness of the method. Test results show that the axial force of the RC frame column varied drastically under the combined excitation of horizontal and vertical earthquakes. The variation of axial force made the force and failure morphology of the specimen more complicated, and could reduce the strength and ductility of the specimen, which eventually resulted in an asymmetry and a certain “pinch” effect of hysteresis curve.