Structural Behavior of Short Thin-Walled Steel Columns Filled with High Strength Concrete Made of Recycled Aggregate

This paper introduces an experimental work to study the behavior of 12 recycled aggregate concrete-filled steel tubular (RACFST) short columns with high-strength concrete grade subjected axial compression loading. These formed from six different cross-sections involving triangle, elliptical, and hexagon, whereas other three sections included traditional forms for control purposes, square, rectangular, circular. All RACFST used are made mild plates. were divided into two groups. The tube thickness was only parameter modified its effect properly. In addition, search best effective section concerning properties stability confinement, so these designed that cross-sectional areas tubes approximately equal. Also, composite action level ductility studied. ultimate failure load, reduction in column length, pattern cross-section shape, lateral displacement recorded during test. Regarding groups (1 2) mm thick plates, testing data obtained elliptical circular respectively showed better confinement ability withstand a higher stress. Moreover, polygonal when number ribs plates model or increased angle between sides is (90°) more, can achieve more respectively. general , increasing increases. Finally, all columns, values contribution ratio (C.C.R) led increase strength index (S.I.) values. An final stresses accompanied this increase.