型钢混凝土异型中节点抗震性能试验研究及设计建议

Experimental study on seismic behavior of SRC abnormal interior joints and design advice

由于工艺要求,大型型钢混凝土核电厂主厂房结构中普遍存在错层、变梁变柱截面而形成的异型中节点。为研究型钢混凝土（SRC）异型中节点的抗震性能,进行了8个1/4缩尺比的SRC异型中节点拟静力试验,考虑了两侧梁错位高度、单侧梁截面高度减小和轴压比等影响因素,分析了SRC异型中节点的破坏形态、滞回性能、承载力、刚度退化、耗能能力及延性等。结果表明：SRC异型中节点主要发生核心区剪切破坏,与SRC常规中节点不同,异型中节点首先沿核心区长对角线出现裂缝,而沿短对角线出现的裂缝则有所滞后,可将核心区长对角线出现裂缝作为判断节点开裂的主要标志;当两侧梁错位时,柱有效计算长度减小,承载力较常规节点有明显提高,变形能力则有所降低;随着两侧梁错位高度的增大,节点承载力增大,延性和耗能能力则减小。当一侧梁截面高度减小时,节点刚度和承载力明显降低,变形能力则有所提高;一侧梁截面高度减小越大,承载力下降越明显;建议小梁截面高度不宜小于大梁截面高度的1/2。当轴压比小于0.5时,增大轴压比可以提高异型节点承载能力,但变形能力会降低,建议轴压比不宜过大。

Due to technical requirements, abnormal interior joints are usually formed at split-level, variable beams and columns in the large-scale SRC nuclear power plant. In order to study the seismic behaviors of SRC abnormal interior joints, the quasi-static tests on eight 1/4 scaled SRC abnormal interior joints were carried out to analyze the failure patterns, hysteretic performance, bearing capacity, stiffness degradation, energy dissipation capacity and ductility of the abnormal interior joints. The influences of the differential height at the split-level between the beams on the two sides, the decrease of beam depth on one side and axial compression ratio were also considered. The results show that ： the dominant failure mode is mainly shear failure in the core area for SRC abnormal interior joints. It is different from SRC conventional joints that the crack appears at first along the long diagonal line. Then the crack develops along the short diagonal line with the repeated loads. So the occurrence of the crack along the long diagonal line can be regarded as the main criteria to judge the joints cracking. Split-level between the beams on the two sides can cause the decrease of effective calculation length of the column. As a result, the bearing capacity is obviously improved compared with the conventional joints. However, the deformability is reduced to a certain extent. As the height of split-level increases, the bearing capacity of joints increases as well, but the ductility and energy dissipation capacity of joints decrease. The decrease of height of beam on one side can cause the reduction in the stiffness and the bearing capacity of joints obviously compared with the conventional joints, but the deformability is improved to a certain extent. And the larger the height of beam on one side is decreased, the worse the bearing capacity of joints becomes. So the suggestion can be made that the height of the small beam should not be less than 1/2 of the large beam. When the axial compression ratio is less than 0. 5, the bearing capacity of abnormal joints can be improved by increasing the axial compression ratio, but the deformation capacity is reduced. So it is proposed that the actual axial compression ratio should not be too large.