Structural response of ultra-high-performance concrete (UHPC) columns under eccentric loads

Abstract

The research investigates the structural response of ultra-high-performance concrete (UHPC) columns under eccentric compression using experimental and nonlinear finite element analysis (NLFEA). Eight slender UHPC columns with an average concrete compressive strength of 133 MPa were tested under eccentric loading. The main experimental variables were: column slenderness ratio (6, 12, and 18), load-eccentricity ratio (0.1, 0.2, and 0.5), and the inclusion of a 2% volumetric ratio of steel fibers. Performance metrics such as failure pattern, load-lateral displacement relationship, ductility, and steel reinforcement strain were used to assess the columns' behavior. ANSYS15 is used to develop NLFEA for the tested columns. The column ultimate load and mid-height lateral displacement analytical results have an average difference of 3.75% and 23%, respectively, when compared to experimental results. The results showed that high slenderness ratios or high load-eccentricity ratios reduce column load-carrying capacity but enhance ductility and crack patterns. Short, low eccentric columns experienced sudden failure, where 1.4% of stirrups failed to confine the column core after the spalling of the concrete cover. The inclusion of 2% steel fibers restrained the spalling and crushing of the slender UHPC columns and enhanced the column ductility.