EXPERIMENTAL ASSESSMENT OF CONCENTRICALLY LOADED PRE-STRESSING CONCRETE-FILLED STEEL TUBULAR COLUMNS

摘要

Although expansive additives are frequently used in contemporary concrete-filled steeltubular (CFST) structures to improve the bond between concrete and steel tubes, littleinformation is available regarding their influence on the mechanical characteristics ofCFST columns. This reflects the pressing need to investigate the impacts of the prestressingachieved through the expansive additives, especially on the concreteconfinement and axial load capacity of CFST. This paper thus discusses the results ofconcentric load tests carried out for 12 pre-stressing CFST columns to assess their axialload capacity and modes of failure. The main parameters investigated are the concretecompressive strength (40, 50 and 90 MPa) and the dosage of the expansive agent (0%,6%, 12% and 24% by mass of cement). The results indicate that the axial load capacityis improved by increasing both the concrete compressive strength and the expansiveadditive dosage. The expansive additive has an important influence on the confinementeffect of CFST. The paper presents new test results that contribute to fill a gap in theliterature and provides insights into the behavior of concentrically loaded pre-stressingCFST columns.