Study on Mechanical Properties of Steel Frame Structure with PEC Columns

Abstract

PEC column has a wide prospect for strengthening existing steel structure buildings because of their high strength, stiffness, and bearing capacity. The seismic performance of the original steel structure could be significantly improved by filling the trough of section steel with concrete to form a partially encased composite column. Especially for multi-story buildings, the PEC column is an ideal edge restriction structural element, so it is of great significance to study its seismic performance. PEC column was introduced into steel frame structure, and six models of 8-story steel frame structures with PEC columns were established by using OpenSees finite element software. The displacement load curve, the maximum axial force in the column, the maximum bending moment at the column base, and the maximum inter-story shear force were obtained by Pushover analysis. The influence of concrete grade and the width-thickness ratio of the steel sheet of the PEC column on the mechanical properties of the whole structure was studied. Results show that lateral stiffness, ductility, and shear load-bearing capacity of the structure are improved with the addition of concrete in section steel, but ductility of the structure decreases with an increase of concrete strength grade. The influence of variation of PEC column parameters on the bottom of the structure is better than that on top. The width-thickness ratio of the section steel flange plays a major role in controlling the mechanical properties of the structure. The elastic stiffness of the structure, axial force of the column, and bending moment of the column base increase with the increase of flange thickness as section height is the same. An increase of the width-thickness ratio of the flange can improve the shear force of the story, and the lower the number of stories, the more significant the effect is.