Lateral torsional buckling of ultra-high-performance fibre-reinforced concrete girders

Abstract

Ultra-high-performance fibre-reinforced concrete (UHPFRC) is a relatively newly developed construction material that not only has high compressive strength (greater than 150 MPa), but also high tensile strength (10–20 MPa). The use of UHPFRC enables the design of slender structural members; hence, instability could become a major governing failure mode. However, the estimation of buckling strength for a concrete structure is not easy, owing to its material characteristics. In this paper, the lateral torsional bucking behaviour and strength of ultra-high-performance concrete I-beams are discussed. A methodology is introduced to obtain the effective moment of inertia of UHPFRC I-beams, considering tensile cracks. By using the effective moment of inertia, the linear elastic buckling strength can be calculated. In addition, the inelastic lateral torsional buckling behaviour is investigated through finite-element analysis. A generalised buckling strength curve with a slenderness parameter is discussed. As a result, the limitations for classification of compact and non-compact members are defined, and lateral torsional buckling strength equations are suggested for a simply supported UHPFRC I-girder subjected to centre point loading. Several experimental studies were also conducted, and the results are applied to verify the final results.