EXPERIMENTAL STUDY ON THE BEHAVIOUR OF L-SHAPED COLUMNS FABRICATED USING CONCRETE-FILLED STEEL TUBES UNDER ECCENTRIC LOADS

Abstract

In this study, the eccentric compression properties of L-shaped columns fabricated using concrete-filled steel tubes connected by double vertical steel plates (LCFST-D columns) were experimentally studied. The eccentricity was used as a parameter to analyse the deformation development, failure mode and ultimate carrying capacity of these columns. The test result indicated that the LCFST-D columns had a good ductility and bearing capacity. Compared with LCFST columns under identical eccentricity, the LCFST-D columns had a higher bearing capacity, over 20%, and significantly higher ductility. The double vertical steel plates filled with concrete efficiently improved the collaboration among the monocolumns, strengthened their integrity and fully utilized the material properties. The test study used a finite element model to analyse the entire deformation process of LCFST-D columns and the interaction among monocolumns to determine the effects of the eccentricity, vertical steel plate thickness, and steel pipe thickness on the performance of these columns under eccentric compression. The test result showed that overall bending and buckling were the failure modes of the LCFST-D columns, during which the three monocolumns bulged first. The eccentricity was a key factor that affected the eccentric load bearing capacity of these columns. Increasing the eccentricity notably decreased the bearing capacity of the columns. Increasing the steel pipe thickness delayed the local buckling of a monocolumn, which increased its bearing capacity. Based on this analysis, a formula to predict the eccentric compression capacity of LCFST-D columns was proposed. The error between calculation results and test data was less than 10%, and the accuracy was verified by the test results.