方钢管型钢再生混凝土组合短柱偏压性能试验研究

Experimental study on eccentric compression performance of recycled concrete filled square steel tube composite short columns

对12个短柱试件进行偏心受压试验,研究方钢管型钢再生混凝土组合短柱的偏压力学性能,观察试件的偏压破坏过程及破坏形态,获取试件的偏压荷载-挠度曲线、荷载-应变曲线、侧向挠度及刚度退化曲线,分析再生混凝土强度、型钢配钢率、方钢管宽厚比、偏心距、再生粗骨料取代率对组合短柱偏压性能的影响规律,研究结果表明:在偏压荷载作用下,各试件的破坏特征较为相似,主要表现为组合柱中部型钢的受压侧最先开始到达屈服状态,随着偏压荷载的继续增加,外部钢管的受压侧也进入屈服状态,最后核心再生混凝土被压碎,组合柱的破坏是由于外部钢管的中部出现了明显的局部鼓曲;试件偏压承载力分别随再生粗骨料取代率和偏心距的增大而逐渐降低,其中偏心距对试件的偏压承载力和侧向挠度影响显著,再生粗骨料取代率对试件偏压承载力和变形能力影响是不利的;增加方钢管壁厚或型钢配钢率均对于提高试件的偏压性能是有利的;提高再生混凝土强度会降低组合短柱的变形能力,这与普通混凝土类似,但试件的偏压承载力会得到相应的增强。总体上,该组合柱在偏压荷载作用下具有较高的承载力和良好的变形能力,研究结论可为该组合柱的工程应用提供一定参考。

The eccentric compression test of 12 short column specimens is carried out to study the eccentric compression behavior of square steel tube reinforced recycled concrete composite short columns. The whole process of eccentric compression and the failure modes of specimens are observed. The eccentric load-deflection curves, load-strain curves, lateral deflection-stiffness degradation curves of the columns are also obtained. The influences of recycled concrete strength, sectional steel ratio, width and thickness ratio of square steel tube, eccentricity and recycled coarse aggregate replacement percentage on t he eccentric compression performance of the composite short columns are mainly analyzed. The results show that similar rules on the failure characteristics for different specimens under eccentric compression can be found, that is, the compression middle steel tube of the composite column yields first and then the compression side steel tube yields. Finally the bulk recycled concrete is crushed. The obvious local buckling in the middle of the square steel tube results in the failure of the composite column. The eccentric bearing capacity of specimens decreases with the increase of replacement ratio of recycled coarse aggregate and eccentricity, in which the eccentricity has a significant effect on the eccentric bearing capacity and lateral deflection of specimens. The recycled coarse aggregate replacement ratio is unfavorable on the eccentric compressive capacity and deformation capacity of specimens. Increasing the wall thickness of square steel tube and the sectional steel ratio is beneficial to the improvement of eccentric compression performance of specimens. Similar to ordinary concrete, as the strength of recycled concrete increases, the eccentric bearing capacity of specimens can be enhanced, while the deformation capacity of specimens decreases. Generally speaking, the composite column has high bearing capacity and good deformation capacity under eccentric compression loads. This work would provide some reference for engineering applications of the composite columns.