高寒环境温度下圆钢管混凝土短柱轴压性能试验研究

Experimental study on axial compression performance of CFST stub columns under very-cold ambient temperature

针对高寒环境温度对钢管混凝土结构力学行为影响显著的问题。开展钢管混凝土短柱轴压性能试验,分析试件在不同温度下的试验现象及破坏形态,探究不同环境温度对圆钢管混凝土短柱轴压力学性能的影响规律,揭示温度对钢管混凝土套箍效应的影响机理;针对现行规范在钢管混凝土承载力计算中未考虑温度作用的不足,基于试验结果分析提出考虑环境温度的钢管混凝土短柱承载力计算修正公式。结果表明:温度变化对钢管混凝土短柱承载力和延性影响显著,随着温度的下降,试件承载力增大,而延性大幅降低,脆性显著增大;温度从40℃降至-40℃,M型、L型试件承载力分别提高27.8%和34.3%;环境温度对构件套箍效应影响明显,套箍率越小越显著;提出的考虑温度影响的钢管混凝土短柱轴压承载力计算修正公式具有较好的可靠性和精度,可为高寒大温差地区钢管混凝土结构的设计提供必要依据。

In view of the significant influence of very-cold ambient temperature on the mechanical behavior of concrete-filled steel tubular(CFST)structure,the axial compression performance test on CFST were carried out,the test phenomenon and the failure modes of specimens at different temperatures were analyzed,the influence laws of different ambient temperatures on the axial compression performance of CFST stub columns were explored,and the influence mechanism of temperature on the confinement effect of CFST is revealed.In view of the insufficiency of current specifications in calculating the bearing capacity of CFST without considering temperature,a modified calculation formula for bearing capacity of CFST stub columns considering environmental temperature is proposed based on the analysis of test results.The results show that the temperature change has a significant impact on the bearing capacity and ductility of concrete-filled steel tube stub columns.With the decrease of temperature,the bearing capacity of specimens increases,while the ductility decreases greatly,resulting in a significant increase in the brittleness.The bearing capacity of M-type and L-type specimens increases by 27.8%and 34.3%respectively when the ambient temperature drops from 40℃to-40℃.The ambient temperature has a more significant influence on the confinement effect of the components with smaller confinement ratio.The modified calculation formula of axial compression bearing capacity of CFST stub columns considering the influence of temperature has better reliability and accuracy,and hence it can provide necessary basis for the design of CFST structures in the areas with very cold temperature and large temperature difference.