高强钢管约束自应力混凝土短柱轴压性能试验

Test on Axial Compression Performance of High-strength Steel Tube Confined Self-stress Concrete Short Column

为了提高工程结构的跨径和抗力水平,本文进行了高强钢管约束自应力混凝土(high-strength steel tube confined self-stress concrete,HSTCSC)短柱的增强机理与受力性能研究,开展了7根大尺寸HSTCSC短柱和1根对比柱的轴压性能试验,试验中所有试件的套箍系数均大于3;讨论自应力混凝土强度、截面类型和截面空心率等因素对HSTCSC短柱的轴压性能影响规律。结果表明:1)自应力混凝土短柱具有明显的脆性劈裂或剪切破坏特征,而HSTCSC短柱具有较好的变形能力和较高的承载力,发生腰鼓型屈曲破坏。2)自应力混凝土在圆形截面高强钢管约束条件下养护比在无约束条件下养护具有更高的弹性模量和强度,自应力混凝土微膨胀作用和高强钢管环向约束的双重作用显著提高了HSTCSC短柱的轴压受力性能。3)自应力混凝土强度和截面空心率的增加均能提高HSTCSC短柱的受力性能,但自应力混凝土强度的增加对HSTCSC短柱受力性能的提升幅度有限,双层圆形截面HSTCSC短柱强化段具有更高的刚度,明显优于单层圆形截面HSTCSC短柱的受力性能。4)圆形截面高强钢管对自应力混凝土的约束能力优于方形截面高强钢管,自应力混凝土强度的增加对方形截面HSTCSC短柱轴压性能的影响不明显,且空心率的增加会显著降低双层方形截面HSTCSC短柱的变形性能。

In order to improve the span and resistance level of engineering structures,the strengthening mechanism and axial compression performance of the high-strength steel tube confined self-stress concrete(HSTCSC)short column was studied in this paper.Seven large size HSTCSC and one control short columns were tested to investigate their uniaxial compression performance;the confining coefficient of all specimens in the test were greater than three.The influence of the self-stress concrete strengths,the types and hollow rates of the cross section on axial compression performance of the HSTCSC short columns was discussed in detail.Results showed that:1)the HSTCSC short columns presented obvious waist drum-type failure mode with significant brittle splitting or shear disruption features,and it possessed an high axial bearing capacity and deformation performance.2)The elastic module and compression strength of the HSTCSC short columns under the confined condition of steel tube were higher than that of the non-confined condition.Moreover,the axial compression properties of HSTCSC short columns were significantly improved by the interaction of self-stress concrete micro-expansion and hoop constraint of high-strength steel tube.3)The mechanical performance of the HSTCSC short columns was greatly improved with the increase of self-stress concrete compression strength and section hollow rate;however,the influence of the increasing self-stress concrete compression strength on the mechanical performance is limited.The mechanical properties of the HSTCSC short columns with double-layer circular section had a higher reinforcement segment stiffness,which was better than that of the single-layer circular section.4)The constraint performance of circular sectional high-strength steel tube on self-stress concrete was better than that of the rectangular section,and the effect of the increasement of section hollow rate on the axial compression properties of the HSTCSC short columns was not obvious.Moreover,the deformation performance of the HSTCSC short columns with double-layer circular section will be decreased with the increase of section hollow rate.