大径厚比下钢管RC柱抗震性能对比研究

Comparative study on seismic behavior of steel tubular RC columns with a large diameter-to-thickness ratio

配筋钢管混凝土(Reinforced concrete filled steel tube,RCFST)柱和钢管约束钢筋混凝土(Steel tube confined reinforced concrete,STRC)柱为钢管RC组合柱的2种主要形式,规范对各自径厚比给出了建议取值,但存在叠合区。为了探究叠合区大径厚比下2类柱的抗震性能及其适用性,以轴压比为主要影响因素,对2组试件开展低周反复加载试验。结果表明:各试件均发生压弯破坏,RCFST柱根处钢管形成环状鼓曲,STRC柱切缝处钢管未见鼓曲;相对于STRC柱,RCFST柱承载力较高,滞回曲线较饱满,耗能能力较强,但曲线下降较快,延性较差;增大轴压比时,RCFST柱承载力下降了5.5%,STRC柱承载力提高了33.8%且延性仍良好。采用数值计算方法扩充结构参数范围,进一步分析径厚比、钢管强度和配筋率对承载力、变形能力及N-M曲线影响。最后给出2类柱的建议适用范围。

Reinforced concrete-filled steel tube(RCFST)columns and steel tube confined reinforced concrete(STRC)columns are the two typical columns of steel tubular and reinforced concrete(RC)composite columns,and the specifications give recommended values for their respective diameter-thickness ratio,but there exists an overlap zone.To explore the seismic behavior and applicability of the two typical columns with a large diameter-to-thickness ratio in the overlapping area,lateral cyclic force and constant axial loading tests were carried out on the two groups of specimens with axial compression ratio as the main influencing factor.The results show that the steel tube root of the RCFST column generates annular buckling,but no obvious buckling is found at the cutting seam of the STRC column.Compared with the STRC column,the RCFST column has a higher bearing capacity,fuller hysteresis curve,and stronger energy dissipation capacity,but the curve decreases rapidly after the peak and the ductility is poor.When the axial load ratio increases,the bearing capacity of the RCFST columns decreases by 5.5%,while that of the STRC column increases significantly by 33.8%and the ductility is still good.Furthermore,the finite element model was used to expand the range of structural parameters,and the influence of the diameter-thickness ratio,steel tube strength,and reinforcement ratio on bearing capacity,deformation capacity,and N-M curves were analyzed.Finally,the suggested range of the two typical columns was given.