Eccentric compression behavior of UHPC encased high-strength steel columns based on experimental and numerical study

Based on 9 experimental columns and 124 numerical simulation models, this paper investigated the eccentric compression behavior of UHPC encased high-strength steel (UEHSS) columns of key parameters: slenderness ratio, eccentricity, steel ratio, UHPC strength and steel section strength. The mechanical performance of UEHSS column under eccentric compression was analyzed by examining the differences and similarities in load-deflection curves, damage modes, bearing capacity, stiffness, ductility and deformation capacity across various experimental parameters. Experimental results indicate that UEHSS columns under eccentric compression invariably fail through lateral buckling around the weaker axis. Increased slenderness ratio and eccentricity reduce both bearing capacity and stiffness of column, though eccentricity exerts a stronger influence on bearing capacity than slenderness ratio. At high eccentricity levels, the effect on column stiffness diminishes. The deformation capacity of columns exhibited an increasing trend with rising steel ratio and eccentricity. Based on the influence of different Concrete Damaged Plasticity (CDP) model parameters of UHPC on mechanical property of UEHSS column, the most suitable CDP model parameters for UEHSS columns were adapted. Based on experimental and simulated result, the accuracy of numerical simulations in predicting the eccentric compression behavior of UEHSS columns under varying experimental parameters was investigated. Furthermore, an extended parameter discussion and analysis were conducted on key parameters influencing the eccentric compression performance of UEHSS columns, establishing the patterns of influence exerted by different experimental parameters on this performance.