火灾后十字形型钢混凝土柱单向偏心受压力学性能试验研究

Experimental Investigation on Mechanical Properties of Cross-Special-Shaped Steel Reinforced Concrete Column Subjected to Uniaxial Eccentric Compression after the Fire

对4根十字形型钢混凝土柱进行了火灾后的力学性能试验研究,并按照ISO834标准升温过程曲线进行火灾试验。1根未受火试件作为对比。异形柱采用桁架式配钢形式,横向腹杆间距为260mm。试件通过静力荷载作用下的单向偏心受压试验,研究加载偏心距对力学性能的影响。通过试验,得出了试件的破坏形式以及极限承载力、截面平均应变分布、柱中侧向位移曲线、荷载-滑移曲线和截面特性。试验结果表明:(1)受火1小时后的十字形型钢混凝土柱仍然具有较高的竖向承载力;(2)试验测量的混凝土与槽钢之间滑移较小,说明型钢与混凝土之间能够协同工作,平截面假定在十字形型钢混凝土柱的截面中仍然适用;(3)在90°荷载角的作用下,十字形型钢混凝土柱会发生单向弯曲;(4)随着荷载的增加,挠度曲线存在水平段,说明火灾后型钢混凝土柱仍具有较大的后期变形能力,并且随着偏心距的增大,试件的变形能力更强。

Experimental investigation on mechanical properties of four cross-special-shaped steel reinforced concrete columns after the fire was carried out in this paper. Fire tests adopt ISO834 standard temperature rising process curve, and one column not subjected to fire test was selected for comparison. Specially-shaped columns are in the form of steal truss, its spacing between transverse web members is 300mm, in the experiments. Specimens were subjected to uniaxial eccentric static compression, considering the influence of load eccentrisity. Based on experiment, the failure mode and ultimate bearing capacity of specimen, the average strain distribution on the cross-section, the lateral displacement curve at column middle part, load-slip curve and section characteristics were all obtained. Experimental results show that （1） after one hour fire test, the cross-special- shaped steel reinforced columns still present higher vertical bearing capacity; （2） the measurement of bond-slip between concrete and steel is small, which indicates that steel and concrete are able to work collaboratively, and the plane cross-section assumption is still applicable in the cross-section of this type of steel reinforced concrete columns; （3） under 90° loading angle, SRC columns present unidirectional bending; （4） along with the increase of load, the deflection curve has a horizontal section, which indicates that after the fire, SRC columns still have large later deformation capacity, and with the increase of eccentricity, the deformation ability of test piece is stronger.