Concreto leve aplicado a pilares mistos preenchidos de aço e concreto

Abstract

The use of concrete filled steel tube (CFST) has been gaining ground as a constructive solution due to the advantages conferred by the joint work of tubular profiles and their concrete core. Structural lightweight concrete can significantly reduce the self-weight of structures due to its lower specific mass. In this context, this work aimed to evaluate the structural behavior of CFST consisting of cold-formed steel profiles and lightweight structural concrete made with lightweight expanded clay aggregate. Initially, the characterization of lightweight concrete and normal specific mass, referential, was carried out by carrying out tests of axial compression, specific mass, tensile strength and static and dynamic modulus of elasticity. The lightweight concrete investigated showed an average compressive strength of 29.55 MPa and 1.510 kg/m3 of apparent specific mass. Then, 43 composite pillars with a rectangular cross-section (127 mm x 100 mm) were fabricated, varying the thickness of the metallic profile in (1.5 mm; 2.0 mm; and 3.0 mm), as well as the length of columns in (381 mm; 635 mm; and 1,270 mm), all filled with lightweight structural concrete. The 43 prototypes were tested under axial compression, seeking to evaluate the influence of local and global slenderness parameters, column failure mode and comparison of their resistant capacities to the normative predictions of NBR 8800 (ABNT, 2008), EUROCODE 4 (2004) and ANSI/AISC 360 (2016). In general, the columns showed a predominant failure mode due to local buckling of the metallic profile and shearing of the concrete core. Evidenced resistant capacities were 5% to 23% lower than those of NBR 8800, EUROCODE 4 and ANSI/AISC 360.