高轴压比高强混凝土足尺框架柱抗震性能研究

Research on seismic behavior of full-scale high-strength concrete frame columns with high axial compression ratios

对9个高轴压比、高强纵筋、高强箍筋、高强混凝土井字箍矩形截面足尺框架柱进行了水平低周反复荷载作用下的抗震性能试验研究,讨论了其破坏机理、破坏形态和滞回特性,分析了轴压比、混凝土强度、箍筋形式及配箍率等因素对试件滞回曲线、骨架曲线、刚度、承载力及延性的影响规律。研究表明:足尺框架柱破坏时混凝土脱落较为严重;高轴压比、高强钢筋、高强混凝土矩形截面足尺框架柱的滞回曲线较为扁平,耗能亦较差,下降段较陡且延性较差;柱中部箍筋非加密区由于纵向钢筋受压失稳而发生破坏导致试件的滞回曲线很扁,且几乎没有下降段;随着混凝土强度等级提高,骨架曲线的最大荷载对应的位移和极限破坏荷载对应的位移均较小,骨架曲线的下降段亦较陡。建议对高轴压比高强混凝土框架柱应沿着整个柱高加密箍筋。

Based on experimental study on the seismic behavior of 9 rectangular frame columns with high axial compression ratios, high-strength full-scale high-strength concrete （HSC） longitudinal reinforcements and transverse reinforcements and rectangular and interlocking ties, their failure mechanism, hysteretic behavior were discussed. The effects of axial compression ratios, concrete strength, arrangement of confinement reinforcement and transverse reinforcement volume ratios on the hysteretic curves, skeleton curves, rigidity, bearing capacity and ductility of specimens were analyzed. The main results are as follows. The breaking off of concrete for full-scale column is relatively severe; The hysteresis loops of HSC rectangular frame columns with high axial compression ratios and highstrength steels are flatter, and have less energy dissipation capacity, and the descending parts of the hysteresis loops are steeper; The hysteresis loops of the columns whose brittle failures caused by buckling unstability of longitudinal reinforcements in the upper less confinement reinforcement regions are much flatter and almost have no descending parts. With concrete strength increasing, all the displacements at the maximum loads and the ultimate failure are relatively smaller and the descending parts of the backbone curves are also steeper. It is suggested that the stirrup＇ s crowding region of HSC frame columns with high axial compression ratios must be along the whole height of columns.