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

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.