椭圆形GFRP-混凝土-钢组合空心柱的轴压性能试验研究

Behavior of elliptical GFRP-concrete-steel double-skin tubular columns under axial compression

椭圆形GFRP-混凝土-钢组合空心柱由椭圆形GFRP外管、钢内管以及两管之间的填充混凝土组成。进行了大尺寸椭圆形GFRP-混凝土-钢组合空心柱的轴压性能试验,所有试件的内部钢管采用了椭圆形截面,试件的高度为600 mm,长轴为300 mm,短轴分别为150、200、250 mm和300 mm。研究了椭圆形截面的长轴与短轴之比、GFRP厚度及试件空心面积率对其轴压性能的影响。研究结果表明:椭圆形GFRP-混凝土-钢组合空心柱中的混凝土在GFRP管和钢管的共同约束下,其承载力和延性较素混凝土大幅提升;随着椭圆长轴与短轴之比的增大,内部约束混凝土的峰值应力有随之增大的趋势;较大的空心面积率并不会减小GFRP和钢管对于混凝土的约束作用;GFRP厚度的增加将会提高椭圆形组合空心柱试件的极限应力和极限应变。

The elliptical FRP-concrete-steel double-skin tubular column(elliptical DSTC) is a novel form of elliptical column which consists of an elliptical outer tube made of FRP, an inner tube made of steel, and an annular layer of concrete filled in between. Elliptical DSTCs have many advantages, such as light self-weight, excellent corrosion-resistance and exceptional seismic behavior, different bending stiffness around two axes of symmetry, which has a promising potential to be used as hollow bridge piers. Tests of elliptical DSTCs with elliptical steel tubes under axial compression were conducted. The effects of long axis to short axis ratio, FRP thickness and void area ratio were investigated. These specimens had a height of 600 mm, a long axis of 300 mm, and different short axes(i.e., 150 mm, 200 mm, 250 mm, and 300 mm). Experimental results show: the concrete in elliptical DSTCs is well confined by the FRP tube and the steel tube, leading to excellent enhancement of strength and ductility;the peak stress of the confined concrete has a trend to increase with the increase of the long axis to short axis ratio;a larger void area ratio does not reduce the confinement effect of FRP tube and steel tube on concrete;the increase of FRP thickness would increase the ultimate stress and strain of confined concrete in elliptical DSTCs.