Experimental and numerical study for lightweight R.C beam under flexural and torsion behaviour

This paper aims to study the behaviour of lightweight R.C. beams under different loads. Six R.C. beams were cast with dimensions of 200 × 250 mm and a length of 1800 mm. These R.C. beams were divided according to their compressive strength: the first group consisted of three beams with normal compressive strength lightweight concrete, and the second group consisted of three beams with high compressive strength lightweight concrete. Also, these beams were divided according to the type of applied load (pure torsion behaviour, flexural behaviour, or combined flexural and torsion behaviour). The load–deflection curve was recorded for R.C. beams subjected to a flexural load, and the torsional moment-twist angle curves were also recorded for R.C. beams subjected to combined bending and torsion as well as pure torsion. Also, by using the digital image correlation D.I.C to investigate the strain behaviour of R.C. beams. By using the ABAQUS software, the results of the experiment were calibrated. After that, the ABAQUS program is used to model the finite element model and carry out a parametric study. This study produced twelve normal and high-strength ordinary concrete beams to compare them with the practical results of lightweight concrete beams. According to the numerical results, the strength and deformation capacity of the ordinary concrete R.C. beam with both normal/high compared to the lightweight concrete R.C. beams improved by approximately 1.21, 1.28, 1.02, 1.07, 1.158, and 1.06, respectively. Additionally, raising the ratio of flexural reinforcement significantly impacts the beams’ capacity load.