方、圆钢管再生混凝土长柱轴压性能试验对比分析

Comparative analysis of axial compression test of recycled aggregate concrete filled square and round steel tube long columns

设计7个圆钢管再生混凝土长柱和7个方钢管再生混凝土长柱,对其进行轴向加载试验,考虑钢管壁厚、长细比和添加块体3个因素,观察试件受力的全过程和破坏形态,得到轴向承载力、轴向荷载-轴向位移曲线、轴向荷载-跨中侧向挠度等数据,分析3个因素对方、圆试件破坏过程和特征、承载力和初始轴向刚度等影响的异同。试验对比分析表明:方、圆钢管再生混凝土长柱轴压受力过程均经历了弹性阶段、屈服阶段和破坏阶段,方形试件破坏形态有柱端压曲破坏和整体弯曲失稳破坏,而圆形试件破坏形态均为整体弯曲失稳破坏;随着钢管壁厚增大,方、圆形试件的承载力均有所提高,但方形试件承载力提升的速度更快,对初始轴向刚度影响甚微。随着长细比增大,方、圆形试件承载力和初始轴向刚度下降趋势一致。添加块体,造成方、圆形试件的承载力微小降低,对试件初始轴向刚度基本上没有影响。圆形试件的侧向挠度变形曲线满足正弦半波的假定;而方形试件的侧向挠度变形曲线不能满足正弦半波的假定。

Axial static monotonic loading test was carried out on 7 recycled aggregate concrete filled round steel tubular long columns and 7 recycled aggregate concrete filled square steel tubular long columns.The changing parameters including the steel tube wall thickness,slenderness ratio and adding block were considered.The whole loading process and failure modes were observed,the axial bearing capacity,axial load-axial displacement curve and axial load-mid-span lateral deflection data were obtained,the influence of different factors on failure process and characteristics,bearing capacity and axial stiffness were analyzed.The comparative analysis shows that the axial compression progress of square and round specimens all goes through the elastic stage,yield stage and failure stage.With the increase of steel tube wall thickness,the bearing capacity of square and round specimens increases,and has little effect on the initial axial stiffness.With the increase of slenderness ratio,the bearing capacity and the initial axial stiffness of square and round specimens decreases in the same trend.The addition of blocks results in a slight decrease in the bearing capacity of the square and round specimens,which has a greater impact on the bearing capacity of the square specimens,and basically has no impact on the initial axial stiffness of the specimens.The lateral deflection deformation curve of the round specimen satisfies the assumption of sine half wave;The lateral deflection curve of the square specimen cannot satisfy the assumption of sine half wave.