圆钢管约束混凝土轴压构件长期持荷后受力性能试验研究

Mechanical behavior of steel tube confined reinforced concrete stub columns after long-term service loading

钢管约束混凝土柱受力性能优越、施工方便,在超高层建筑等领域有广阔的应用前景。但现有研究仅针对短期性能与抗震性能展开,缺乏长期性能研究,针对钢管约束混凝土柱长期持荷后受力性能的研究尚未见报道。鉴于准确预测构件轴压承载力等相关受力性能指标对保证结构安全至关重要,在圆钢管约束混凝土轴压构件长期持荷试验(持荷时间490 d)结束后,进行了相应徐变后受力性能试验。共设计18个圆钢管约束混凝土短柱试件,主要参数为持荷试验加载龄期、含钢率、钢-混凝土界面黏结摩擦等,研究了长期持荷作用对试件刚度、轴压承载力、峰值应变的影响,并分析了其对约束效应及钢管纵向受力的影响。研究结果表明:长期持荷在略微提高轴压承载力的同时,会减小峰值应变,减小幅度达4.8%~20.0%,且该影响对早龄期加载试件更为显著。此外,长期持荷对约束效应及钢管纵向受力的影响不明显。

Steel tube confined reinforced concrete(STCRC)columns have a promising future in high-rise buildings,due to their excellent mechanical behaviour and ease in construction.To date,investigation is limited for the influence of the long-term sustained loads on the mechanical behaviour of STCRC columns despite the extensive research outcomes achieved in the short-term and seismic behaviour of STCRC columns.As the key bearing members,it is important to accurately predict the mechanical behaviour of STCRC columns for structure safety.Hence,18 STCRC stub columns were loaded axially to failure after 490 days of service loading to experimentally investigate the mechanical behaviour of STCRC stub columns after long-term service loading.The considered parameters include the loading age of the long-term tests,the steel content ratio and the interface bond condition of the steel-concrete interface.The influence of the long-term sustained loads on the axial stiffness,ultimate strength and peak strain was investigated.The influence of the long-term sustained loads on the confinement effects and the vertical force contribution of steel tubes in the axially loaded STCRC stub columns were particularly investigated.Test results show that the sustained loading would slightly increase the ultimate strength and decrease the peak strain of STCRC columns by 4.8%-20.0%,while these kinds of influences are more significant for STCRC columns with early age loading.The influence of the long-term loads on the confinement effects and the vertical contribution of the steel tube is limited.