基于套管屈曲约束的拉挤型GFRP管轴压性能

为解决复合材料空间桁架结构部分关键压杆失稳引发的连续性倒塌问题，提出了一种由不锈钢套管及螺栓连接系组成的玻璃纤维增强树脂复合材料(GFRP)管整体失稳套管屈曲约束装置。为分析该套管屈曲约束装置对拉挤型GFRP管轴压性能的影响，对3个GFRP管试件和4个套管屈曲约束GFRP管试件进行了轴压试验，观察了试件的受力过程和破坏形态，获得了荷载-位移曲线和荷载-应变曲线，对比研究了两者的极限承载力和破坏模式，同时利用有限元模型分析了不同内核长细比、内核与套管间隙及套管壁厚对GFRP管轴压性能的影响。结果表明:该套管屈曲约束装置能有效约束GFRP管整体失稳变形，其极限承载力和延性均得到提升，并使GFRP管从失稳破坏向材料强度破坏发展；内核长细比越大，套管屈曲约束GFRP管极限承载力相比于内核失稳临界荷载的相对提升幅值越高，约束效果越好；内核与套管间隙越大，GFRP管延性越好，但其极限承载力会降低；套管壁厚过薄会降低GFRP管极限承载力，过厚则约束效果不明显。 

Axial compression performance of pultruded GFRP tube based on casing buckling restraint

In order to solve the problem of continuous collapse caused by the instability of the key compression struts in fiber reinforced polymer (FRP) space truss structure, a casing buckling restrained brace for the overall instability of glass fiber reinforced polymer (GFRP) tubes composed of stainless steel casing and bolt connection system was proposed. In order to analyze the influence of the casing buckling restrained brace on the axial compression performance of pultruded GFRP tubes, axial compression tests were carried out on three GFRP tube specimens and four GFRP tube specimens with casing buckling-restrained brace. The loading course and failure form of specimens were observed, and the load-displacement curves and load-strain curves were obtained, and the ultimate bearing capacity and failure mode were compared. At the same time, the finite element model was used to analyze the influence of different slenderness ratios of GFRP tubes, core and casing gaps and casing thicknesses on the axial compression performance of GFRP tubes. The results show that: the casing buckling restrained brace can effectively restrain the overall instability deformation of GFRP tubes, its ultimate bearing capacity and ductility are improved, and the GFRP tubes develop from instability failure to material strength failure; the larger the slenderness ratio of the core, the higher the ultimate bearing capacity of the GFRP tubes due to buckling of the casing compared with the critical load of the core instability, and the better the restraint effect; the greater the gap between the inner core and the casing, the better the ductility of the GFRP tube, but its ultimate bearing capacity will be reduced; too thin casing thickness will reduce the ultimate bearing capacity of GFRP tubes, but too thick will have no obvious restraint effect.