FRP-混凝土-钢双壁空心管短柱轴心抗压试验研究

Experimental investigation of FRP-concrete-steel double-skin tubular stubs under axial compressive loading

为研究FRP-混凝土-钢双壁空心管短柱的轴压性能,完成了3个圆钢管短柱和10个双壁空心管短柱试件的轴心抗压试验。结果表明:双壁空心管短柱内层钢管受到管内混凝土的径向压力,屈曲被延迟;管内混凝土受到外层FRP管和内层钢管的共同约束;试件具有良好的延性。在轴压力作用下,圆钢管短柱的破坏形态与其径厚比有关。双壁空心管短柱在轴压作用下有3种破坏形态:FRP管的纤维拉断,FRP管的纤维拉断和钢管压屈,整体压屈。破坏形态主要与钢管径厚比、空心率、FRP管的约束程度有关。通过分析本文和国内外相关试验结果,提出了双壁空心管内混凝土受压应力-应变关系模型的3种类型及模型参数的计算公式。模型考虑空心率、内层钢管径厚比、外层FRP管约束程度、FRP层合结构和加载方式的影响,与试验结果符合较好。

To study the axial compressive behavior of FRP-concrete-steel double-skin tubular stubs （ DSTSs）, experiments of 3 circular steel tubes and 10 DSTS specimens were carried out. Test results indicate that concrete in DSTS is effectively confined by the steel tube and the FRP tube, the local buckling of the inner steel tube is either delayed or suppressed by concrete, leading to a ductile behavior. The failure mode of the steel tube is related to its diameter-to-thickness ratio. Three types of failure mode of DSTS are found ： fiber rupture of FRP tube, fiber rupture of FRP tube and buckling of steel tube, as well as buckling of DSTS. The failure modes are relevant to the diameter-to-thickness ratio of steel tube, the void ratio and the amount of FRP confinement. Based on the experimental results of this study and those from related literatures, three types of concrete compressive stress-strain relationship model of DSTS are proposed. The model takes into account the influence of void ratio, diameter-to-thickness ratio of inner steel tube, the confinement of FRP tube, FRP laminate structure and loading method, and agrees well with the test results.