基于性能化设计的RC框架结构破坏机制试验研究

Experimental Study on Failure Mechanism of RC Frame Structures Based on Performance Design Method

为验证广东省标准DBJ/T 15-92—2021《高层建筑混凝土结构技术规程》“二水准、二阶段”抗震性能化设计方法的合理性、可靠性和容错性,设计两批相同的3榀抗震构造等级分别为一级、二级、三级的1∶4缩尺平面RC框架结构试件,加载时各层楼板上布置铁质配重模拟分布荷载,考虑楼板及楼板荷载对框架结构破坏机制的影响。试验采用位移控制单点加载,加载点位于三层楼面梁标高处,在柱纵向钢筋达到屈服应变前为单循环加载,屈服后采用三循环加载。通过拟静力试验,考察结构的抗震破坏形态和破坏机制,分析滞回曲线、延性、刚度、耗能等抗震性能指标的演化规律。试验结果表明:试件损伤破坏的塑性铰发展路径基本相同,符合梁端塑性铰延性机构的破坏机制;试件没有明显剪切破坏特征,承载力利用系数ξ能实现“强剪弱弯”抗震设计要求;6榀框架结构试件的滞回曲线饱满,抗震延性系数范围为4.36~6.10,等效粘滞阻尼系数最大值范围为0.125~0.165,展现了良好的抗震耗能性能;楼板提高框架梁的刚度和承载力,对试件抗震破坏机制有明显影响,试件保持了“强柱弱梁”抗震破坏特征,构件重要性系数η能保证“强柱弱梁”的抗震设计要求;试件破坏特征有随机性,但破坏机制整体规律性较强,不同抗震构造等级试件的梯度特征明显。

To verify the rationality,reliability and fault tolerance of the“two-level and two-stage”seismic performance-based design method of Guangdong standard DBJ/T 15-92-2021“Technical specification for concrete structures of high-rise buildings”,this study designed two batches of 1∶4 scale plane RC frame structure specimens with the same seismic structure grade of first-level,second-level and third-level.During loading,iron counterweights were arranged on each floor to simulate the distributed load,and the influence of floor and floor load on the failure mechanism of frame structure was considered.The test adopted displacement-controlled single-point loading.The loading point is located at the elevation of the three-story floor beam.Before the longitudinal reinforcement of the column reaches the yield strain,it is single-cycle loading,and after the yield,it is three-cycle loading.Through the pseudo-static test,the seismic failure mode and failure mechanism of the structure were investigated,and the evolution law of seismic performance indexes such as hysteresis curves,ductility,stiffness and energy dissipation was analyzed.The test results show that the plastic hinge development paths of the specimen damage are basically the same,which conforms to the failure mechanism of the plastic hinge ductility mechanism at the beam end.The specimen has no obvious shear failure characteristics,and the bearing capacity utilization coefficientξcan meet the seismic design requirements of“strong shear and weak bending”.The hysteresis curves of the six frame structure specimens are full,and the seismic ductility coefficient ranges from 4.36 to 6.10.The maximum value range of equivalent viscous damping coefficient is 0.125~0.165,which shows good seis⁃mic energy dissipation performance.The floor slab improves the stiffness and bearing capacity of the frame beam,which has a significant impact on the seismic failure mechanism of the specimen.The specimen maintains the seismic failure characteristics of“strong column and weak beam”,and the component importance coefficientηcan ensure the seismic design requirements of“strong column and weak beam”.The failure characteristics of the specimens are random,but the overall regularity of the failure mechanism is strong,and the gradient characteristics of the specimens with different seismic structural grades are obvious.