Study on compressive performance of steel-reinforced concrete-filled circular steel tubular members considering preload on steel tubes

To study the influence of the preload effect on the later mechanical performance of steel-reinforced concrete-filled circular steel tubular (SRCFST) members, an experimental study on 12 circular SRCFST columns subjected to compressive loads was completed. Main testing parameters were the preload ratios and load eccentric ratios. The deformation process, failure mode, and the influences of different parameters on the load-deformation curves and mechanical performance of the members were obtained through the test. The testing results show that different preload ratios and load eccentric ratios have a slight effect on the failure mode of specimens, however, the specimens exhibit distinct failure processes due to the varying slenderness ratios. The change of preload ratios has little effect on the ultimate bearing capacity of axially loaded stub columns but has a certain effect on the mechanical performances of eccentrically loaded specimens. With the increase of the preload ratio, the ultimate capacity of the specimen under eccentric compression decreases, the influence of eccentricity on the bearing capacity of specimens within the range of test parameters is significantly greater than that of the preload ratio. Based on the test results, the reliability of the finite element (FE) model was validated. Through the validated FE model, the interaction between steel tube and concrete, and the distribution of bearing capacity of each component were discussed, as well as the influence of various parameters (i.e., slenderness ratio, load eccentricity ratio, cross-section size of profiled steel) on the influential coefficient of bearing capacity was further analyzed. The results show that the preload ratio, eccentricity and slenderness ratio have significant effects on the influential coefficient of bearing capacity. Finally, the calculation method for compressive capacity of SRCFST members considering the preload on steel tube was proposed, and the calculated results are in good agreement with the experimental and numerical results. © 2022, Editorial Office of Journal of Building Structures. All right reserved.