酸性大气环境下多龄期钢框架节点抗震性能试验研究

为研究酸性大气环境下钢材力学性能及钢框架节点抗震性能随锈蚀程度加剧的退化规律，分别对不同锈蚀程度的24个标准钢材材性试件、12个焊接梁柱节点试件进行了单向拉伸试验、低周往复加载试验。基于材性试验数据，建立了钢材屈服强度、抗拉强度、弹性模量和伸长率等基本力学性能指标与失重率之间的线性回归关系，分析了不同锈蚀率及加载制度对钢框架节点试件荷载-位移曲线、骨架曲线、刚度和承载力退化、变形能力、滞回耗能等的影响，获得锈蚀钢框架节点试件承载力、刚度以及耗能能力随锈蚀程度加剧的退化规律。研究结果表明：锈蚀对钢框架节点的破坏形态有着显著影响，随着锈蚀程度的增加，钢框架节点试件的耗能能力逐渐减小，加载后期的承载力急剧下降，而且脆性断裂现象表现得愈发明显；随着水平位移幅值及循环次数的增加，钢框架节点试件的塑性变形累积、刚度与承载力退化明显；在相同锈蚀程度下，试件在变幅加载下的耗能能力最大，混合加载下的次之，等幅加载下的最小。研究成果可为在役钢框架结构地震易损性研究提供试验支撑。

Experimental research on seismic behavior of multi-aged steel frame joint under acidic atmospheric environment

In order to study the degradation law of steel mechanical properties and seismic performance of frame joints with corrosion degree increased in the acidic atmospheric environment, the one directional tensile tests of 24 standard steel material specimens were performed and 12 beam-column joint specimens in different corrosion levels were tested under cyclic loading. Based on material test data, the linear regression relationship between the yield strength, ultimate strength, elastic modulus, elongation and weightlessness rate was established, the influences of different corrosion rates and loading systems on loading-displacement curve, skeleton curve, strength and stiffness degradation, deformability, hysteretic energy dissipation of steel frame joint were analyzed. The degradation laws of load carrying capacity, strength, stiffness and energy dissipation capacity of the corroded steel frame joint with the corrosion degree increased were established. The results show that corrosion has a significant impact on the damage pattern of steel frame joint. With the increase of corrosion degree, the energy dissipation of the specimens decreases gradually, the load carrying capacity falls sharply in the late loading stage and the brittle fracture occurs more obvious. With the increase of displacement amplitude and cycle number, the plastic deformation of steel frame joint is accumulated gradually, the stiffness and strength degradation is obvious. Under the same corrosion degree, the energy dissipation capacity of specimen with variable amplitude loading is the biggest of all, followed by the mixed loading, and the constant amplitude the minimum. The results can provide experimental support for the seismic fragility study of existing steel frame structure.