Axial Compression Behavior of Steel Fiber-Reinforced Rubber Concrete-Filled Double-Skin GFRP Tubular Stub Columns

The FRP–concrete–steel double-skin tubular column (DSTC) is a novel composite column designed to meet the structural demands for high strength, exceptional durability, and lightweight characteristics. To investigate the axial compression performance of DSTCs, this study conducted axial compression tests on 16 circular DSTCs and three circular fully filled columns (FCSCs). This research focused on analyzing the effects of steel tube wall thickness, void ratio, rubber content, steel fiber content, and GFRP tube wall thickness on stub columns’ failure modes, load–displacement curves, load–strain curves, and stress–strain relationships of concrete. The results demonstrated that GFRP tube wall thickness is the most critical parameter influencing the bearing capacity and deformation capacity of the column. The ultimate bearing capacity of all specimens ranged from 1606.9 to 3447.9 kN; the peak displacement of the specimens ranged from 7.49 to 17.77 mm. Increased void ratios decrease bearing capacity but enhance ductility, whereas steel tube wall thickness and steel fiber content have relatively minor effects. Based on the experimental results, models for the ultimate bearing capacity, ultimate strain, and stress–strain relationship of short columns were proposed, taking into account rubber content. The average predicted-to-experimental capacities ratio is 0.97 and the predicted load–displacement curves match well with the experimental curves, indicating the very high accuracy of the proposed models.