Research on compressive behavior of CFRP-confined CFDST stub columns with square stainless steel outer tube

Carbon fiber-reinforced polymer (CFRP)-confined concrete-filled double skin tube (CFDST) stub columns with a square outer tube made of stainless steel can be characterized by their low weight, high strength, and good corrosion resistance. They have good application prospects in the field of ocean engineering. This study applied the finite element software ABAQUS to comprehensively investigate the compressive behavior of CFRP-confined CFDST stub columns with a square stainless steel outer tube and a circular inner steel tube in terms of their ultimate bearing capacity, based on previous experimental research. Through a parametric analysis and comparison, it was found that the strength and width-to-thickness ratio of the outer tube have a significant effect on improving the ultimate bearing capacity of the specimen, while the strength and diameter-to-thickness ratio of the inner tube and the number of CFRP layers have a limited effect. The development stage of the interaction stresses between the inner and outer tubes and concrete was clarified, and the location of the maximum interaction stress was determined. Finally, based on the limit equilibrium method, formulae for predicting the ultimate bearing capacity of square CFDST stub columns and CFRP-confined square CFDST stub columns were derived.