A composite concrete-filled glass fiber reinforced polymer (GFRP) tube square column is a new type of composite column, where GFRP is externally wrapped over several GFRP square tubes to form a multicavity GFRP tube, and then concrete is poured inside. External GFRP wrapping methods can be divided into two types: entirely wrapped and strip-type wrapped methods. The former is superior to the latter in terms of performance under stress. However, difficulties are introduced in the construction process of the former, and substantial materials are required to wrap the entire structure. To examine the axial compressive performance for this new type of composite column and the impact of the wrapping method, we designed and fabricated one type of entirely wrapped composite column and two types of strip-type wrapped composite columns with clear spacings of 85 mm and 40 mm, respectively, and performed static axial compression tests. Through tests and numerical simulations, we obtained the failure mode, load–displacement curve, and load–strain curve of the specimen, and analyzed the impact of the externally wrapped GFRP on the mechanical behavior of the composite column. The results show that the composite column reached the peak load before the fracture of the GFRP tube fiber occurred, and the bearing capacity declined sharply to approximately 75% of the peak load after the fiber fractured, then entered a platform section, thereby displaying ductile failure. As the wrapped layers of GFRP strips increased, the load capacity of the specimen exhibited a linear growth tendency. Compared with the performance of the entirely wrapped method, the load capacity of the specimens in the W5040 group declined 9.8% on average, and the peak efficiency of the GFRP strips increased by 50%, thereby indicating that the use of appropriate GFRP layers and strip distance intervals can ensure the appropriate bearing capacity of composite columns and full utilization of GFRP material properties.

中文翻译：

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复合填充GFRP管方柱的轴向压缩性能

玻璃纤维增​​强复合材料（GFRP）管方柱是一种新型的复合材料柱，将GFRP外包裹在数根GFRP方管上形成多腔GFRP管，然后在里面浇筑混凝土。GFRP外包裹法可分为整体包裹法和条形包裹法两种。前者在压力下的表现要优于后者。然而，前者在建造过程中遇到了困难，需要大量的材料来包裹整个结构。为了检查这种新型复合柱的轴向压缩性能和缠绕方法的影响，我们分别设计制造了一种净距分别为85mm和40mm的全包裹复合柱和两种条形包裹复合柱，并进行了静轴压试验。通过试验和数值模拟，我们得到了试件的破坏模式、载荷-位移曲线和载荷-应变曲线，并分析了外包裹GFRP对复合柱力学行为的影响。结果表明，复合柱在GFRP管纤维断裂前达到峰值载荷，纤维断裂后承载力急剧下降至峰值载荷的75%左右，然后进入平台截面，呈现延性破坏. 随着GFRP带缠绕层数的增加，试样的承载能力呈线性增长趋势。与完全缠绕法的性能相比，W5040组试样的承载能力平均下降了9.8%，GFRP条的峰值效率提高了50%，表明使用合适的GFRP层和条距离间隔可以保证组合柱适当的承载能力和充分利用GFRP材料特性。