Axial Compression Performance of Precast Circular Semi-Continuous Concrete-Filled Steel Tube Columns: Finite Element Analysis and Theoretical Modeling

A new finite element (FE) model was constructed with ABAQUS, and the applicability of the model was verified by the coincidence with typical damage modes and load-compression curves in the tests, and the axial compression performance of the precast circular semi-continuous concrete-filled steel tube (PCSCFST) columns was investigated. The effects of diameter-thickness ratio, slenderness ratio, yield strength, etc. on the axial compression performance of the PCSCFST columns were investigated by parametric analysis. The changes in slenderness ratio, yield strength and diameter-thickness ratio of the upper and lower steel tubes have obvious effects on the bearing capacity of the specimen, while the changes in bolt diameter and diameter-thickness ratio of the outer steel tube have little effects on the bearing capacity. In particular, the diameter ratio of bolt to steel tube (d/D) increases to 1/10, the bearing capacity increases slightly, the ratio (d/D) continues to increase until the bearing capacity decreases slightly, and the bearing capacity appears to increase significantly after the ratio (d/D) reaches 1/7; the yield strength ratio of bolt to upper and lower steel tube (fyb/fy1) increases from 1 to 2, the bearing capacity decreases slightly, and the bearing capacity increases significantly when the ratio (fyb/fy1) reaches about 2. After that, the change is minimal. In addition, a theoretical model was developed to predict the ultimate bearing capacity of the PCSCFST columns, and a close correlation was found between the FE simulation results and the theoretical model. The mean ratio of the FE ultimate load Nu,FE to the predicted ultimate load Nu,pre was 1.006 with a standard deviation of 0.0389.