钢筋混凝土吊脚楼平面框架结构抗震性能试验研究

为研究坡地吊脚框架结构的抗震性能，设计了一栋7层的典型RC（钢筋混凝土）吊脚框架结构，提取顺坡向下部3层2跨平面框架子结构(缩尺比例为1/3)为试验对象，开展吊脚平面框架结构的拟静力试验，观察其裂缝开展过程以及破坏形态，分析其滞回性能、承载能力、延性和损伤路径等抗震性能,并探讨吊脚层的破坏形态。结果表明：子结构呈梁柱分别出现塑性铰的破坏模式，首先在第2层的梁端形成塑性铰，接着在吊脚短柱的下端、与该柱相邻的梁端以及第3层中柱的顶端出现塑性铰，最终破坏以吊脚短柱的混凝土压溃、梁端混凝土脱落以及第3层中柱顶端两侧混凝土剥落为标志；子结构吊脚层的破坏路径为由短柱沿斜坡向下至吊脚长柱发展，第2层的破坏路径为从中柱向两侧边柱发展；子结构吊脚短柱的破坏仍以弯曲破坏为主，合理的设计可实现短柱的强剪弱弯破坏模式；吊脚层各柱抗侧刚度的不均匀性导致了结构的吊脚层柱破坏程度的差异，破坏主要集中于吊脚短柱的下端以及与其相邻的梁端。为防止局部严重损伤，宜改善吊脚层各柱间抗侧刚度的不均匀性。

Experimental study on seismic behavior of plane frame structures of RC stilted buildings

In order to investigate the seismic performance of the stilted frame structure built on sloping field, a typical 7-story reinforced concrete (RC) stilted frame structure was designed. According to the ratio of 1/3, the lower three-story two-span substructure along the slope was extracted as the test object, a quasi-static test of plane frame stilted structure was carried out, the process of crack development and failure mode was observed, and the seismic performance was analyzed in terms of hysteretic behavior, ultimate capacity, ductility and damage path. The failure mode of the stilted floor was discussed. The results show that: the failure mode of the sub-structure is the plastic hinges of beams and columns. First, the plastic hinge is formed at the beam end of the second floor, then the hinge is formed at the lower end of the short column, the beam end adjacent to the column, and the top of the middle column of the third floor. The final failure is marked by the concrete collapse of the short column, the concrete spalling at the beam end and concrete spalling on both sides of the top of the 3-story central column. The failure path of the stilted layer is that the short column develops downward along the slope, and that of the second layer develops from the middle column to both sides. Bending failure is still the main failure mode of the short column where the failure mode of strong shear and weak bending can be realized by reasonable design. The non-uniform stiffness of columns of stilted floor leads to the difference of the damage state of columns at the stilted floor, and the failures are mainly focused on the short column and the adjacent beam end of the stilted floor. In order to prevent serious local damage, it is beneficial to resolve non-uniform distribution of the stiffness between the columns of the stilted floor.