Flexural behaviour of lightweight foamed concrete partially encased steel beam

Purpose The universal beam is widely used as construction material due to its excellent strength-to-weight ratio but high slenderness ratio in the web steel section prone to lateral-torsional buckling (LTB) failure. To improve LTB resistance, the incorporation of modified foamed concrete (FC) in partially encased steel beam (PESB) is proposed. The FC-encased web section of steel beam promotes overall weight reduction and increases its specific strength. However, FC has substantially low strength, but incorporation of siliceous material (such as rice husk ash [RHA]) offers pozzolanic activity to offset the low strength in FC. This study explores the use of a modified FC to encase steel beam, where 40% of fine aggregate is replaced with RHA (hereafter referred to as RHA-FC) to enhance the load-bearing capacity and torsional rigidity. Addition of RHA mitigates the extraction of natural resource due to the reduction of fine aggregate consumption. This study aims to investigate the material properties of RHA-FC and measure the flexural strength of RHA-FC PESB. Design/methodology/approach The experimental work was performed to assess the compressive strength, splitting tensile strength, modulus of elasticity, Poisson ratio and fracture energy of plain FC, RHA-FC and normal concrete (NC). In addition, the flexural strength of PESB was evaluated through the four-point bending test. Findings RHA-FC improved the mechanical properties compared with the FC counterparts. Nevertheless, less satisfactory performance was seen in RHA-FC compared with NC. RHA-FC PESB achieved average 17.87% enhancement in ultimate bending moment compared with bare steel beam counterparts and can reduce lateral torsional buckling with associated zero torsional angle. Originality/value RHA-FC PESB substantially enhances stability and performance and offers a promising alternative in construction applications.