Experimental Investigation on Behavior of SCC Filled Steel Tubular Stub Columns Strengthened with CFRP

Abstract

In the present research, experimental studies have been devoted to investigating the behavior of self-compacting Concrete Filled Steel Tube (CFST) stub columns strengthened by Carbon Fiber Reinforced Polymer (CFRP) laminates. A total of 28 stub columns under monotonic compression load were tested in order to discover the best configuration of the CFRP for confined column system, fourteen specimens with circular cross-sections (100x300) mm and another fourteen specimens with square cross-sections (100x100x300) mm, and each fourteen specimens can be classified into three categories: three hollow steel tube columns, three plain SCC columns, and eight SCC filled steel tube columns. The experimental results indicated that the use of CFRP laminates to strengthen the CFST has a significant effect on the overall behavior of CFST such as enhancement on its strength and ductility. Also the CFRP confinement delays local buckling of steel tube, prevents a sudden strength reduction caused by the local buckling of the steel tube, and increases lateral confinement of the concrete core. It is found that the best configuration of CFRP tubes system is transverse CFRP tube for circular hollow steel tube columns, circular plain concrete columns, circular concrete filled steel tube columns and square plain concrete column with a percent of increase in ultimate load of (31.1%, 254.3%, 43.4%, and 101%) respectively, and longitudinal CFRP tube for square hollow steel tube columns and square concrete filled steel tube columns with a percent of increase in ultimate load of (30.5% and 25.66%) respectively. While the best configuration of CFRP rings system is four rings of 37.5mm width for both circular and square concrete filled steel tube columns with a percent of increase in ultimate load of (24.15% and 17.1%) respectively.