螺旋筋增强方钢管混凝土柱的轴压性能及参数分析

Axial compressive behavior and parametric analysis of spiral reinforcement concrete filled square steel tubular columns

为研究螺旋筋增强方钢管混凝土(SRCFSST)柱的轴压性能,以螺旋筋间距、螺旋筋直径、螺旋圈与方钢管的径宽比、方钢管壁厚、混凝土强度等级、纵筋为变化参数,对23个短柱试件进行了轴心受压破坏试验。基于试验实测数据,就各变化参数对SRCFSST轴压性能的影响规律进行了深入的参数分析,其中在延性分析部分引入了基于耗能的延性系数。研究结果表明:SRCFSST试件的表观破坏形态与普通方钢管混凝土的相似;当螺旋筋配筋率≥1.5%时,荷载位移曲线由下降型转化为强化型,并出现四个关键特征点,破坏前预兆明显;在增加相同用钢量的条件下,增加螺旋筋的含钢量时承载力、峰值应变及延性均大幅提高,而增加方钢管和纵筋的含钢量时仅承载力有小幅提高,峰值应变、延性均无明显变化;基于参数分析的结果,对采用SRCFSST的轴压构件的最优配钢方式提出了设计建议。

To investigate the axial compressive behavior of spiral reinforcement confined concrete filled square steel tubular （SRCFSST） stub columns, a total of 23 specimens were designed to test under axial load. Six parameters were considered, including spiral reinforcement spacing, diameter, ratio of the spiral diameter to the square tube width, square tube width, concrete strength and longitudinal bar. Based on the tested data, the effects of design parameters on axial compressive behavior of SRCFSST were analyzed, and in the ductility part the energy-based ductility factor was introduced. The experiment results show that the failure modes of SRCFSST columns are similar to those of concrete filled square steel tubular columns. When the spiral reinforcement ratio over 1.5%, the type of load-displacement curves by falling into strengthening, and there appeared four feature points in load-displacement curves as the obvious sign before the damage. Under the condition of increasing the same weight of steel, with the increase of content of spiral reinforcement, the bearing capacity, peak strain and ductility were greatly increased, while increasing the content of steel or longitudinal bar, only the bearing capacity improved slightly, and the peak strain and ductility stayed almost unchanged. Based on the parametric analysis results, the design suggestions was proposed for optimal configuration of steel in axial compressive member adopted SRCFSST.