Behavior of eccentrically loaded normal weight concrete encased steel columns at elevated temperature

Abstract

This paper presents an experimental investigation on the behavior of normal weight concrete encased steel (CES) columns eccentrically loaded and exposed to different elevated temperature using an electrical furnace. Four CES columns were tested with cross section dimensions of 150 ×150 mm (width× depth) and 1250mm total length and encased a steel section with dimensions of 70×60× 4×4 mm (total height× flange width× flange thickness× web thickness. The top and bottom ends of the columns were designed as corbels to prevent the premature local bearing failure at the concrete due to axial load. The corbels had a cross section dimensions equal to 240mm ×150mm (width × depth) with a distance between them equal to750mm. The experimental results have revealed that all CES columns have failed by flexural buckling failure mode with concrete crushing at the middle third of the compression side column accompanied with local buckling of the steel section flange. Analysis of the test results has also indicated that when the exposed temperature increases, the failure load considerably decreases. Where, the failure load of the CES columns has decreased by 53.6%, 61.2%, and 63.6% compared to the control CES column when they exposed to temperature of 400°C, 500°C, 600°C, respectively.