圆CFRP-钢管混凝土轴压构件静力性能研究

Study on static performance of concentrically compressed concrete filled circular CFRP-steel tubular members

为了初步了解圆CFRP-钢管混凝土轴压构件的静力性能,进行32个试件的试验研究。试验结果表明,长径比较小的试件属于强度破坏,长径比较大的试件则属于稳定破坏;试件的载荷-中截面挠度曲线可以分为以下三个阶段:弹性段、弹塑性段和软化段。对试验结果的分析表明,在极限荷载之前,钢管纵向应变沿截面高度的分布基本符合平截面假定;钢管和CFRP管在纵向和环向都可以协同工作;环向应变分布不均匀,同一点的纵向应变和环向应变异号,纵向受拉的钢管对混凝土没有环向约束作用;构件的挠曲线近似为正弦半波曲线。最后,应用纤维模型法模拟了圆CFRP-钢管混凝土轴压构件的荷载-中截面挠度曲线,计算结果与试验结果吻合良好,且偏于安全。

Thirty-two specimens were experimentally investigated to study the static performance of concentrically compressed concrete filled circular CFRP-steel tubular members. The test results indicated that, for members with relative small slenderness ratio, the failure is dominated by the strength loss of the materials, whereas for members with relative large slenderness ratio, the failure is controlled by instability. The load versus mid-height deflection curves of the composite member can be divided into three stages, i.e., elastic, elasto-plastic and softening stages. Analysis of the test results indicates that, before the ultimate stage, the distribution of the steel tube longitudinal strains over depth of the cross-section remains approximately linear, the steel tube and its outer CFRP material can cooperate both longitudinally and circumferentially. The distribution of the circumferential strains is not uniform, the longitudinal strain and the circumferential strain of a given point are in opposite signs, and the steel tube tensioned longitudinally has no circumferential confinement effect on its core concrete. The deflection along height of the member is approximately a half sin wave. Finally, the load versus mid-height deflection curves of the concentrically compressed concrete filled circular CFRP-steel tubular members are analyzed using a fiber element approach, and the results agree well with those of the tests, and are on the safe side.