The aim of the paper is to study the behavior and compare the strength of the thin-walled composite beams of different cross-sections for combined bending and torsion loadings. The effect of changing the length of span for various cross-section beams with cantilever support conditions is studied. Three different loadings of uniformly distributed concentric load, torsional moment and eccentric load were considered. The beams were modelled and meshed using a pre-processing finite element tool named HYPERMESH followed by the analysis using the ANSYS 22 software. A comparative analysis for stress developed, deflections and twisting effects for thin-walled composite beams of hollow rectangular, symmetric I section, and channel section with three different laminates of quasi-isotropic, bending stiffness and torsional stiffness are presented. Later an arrangement of cavity wall structure with hollow rectangular, symmetric I and hollow rectangular beam as lintel were analyzed. It was observed that the ANSYS software resulted in much easier modelling, faster and cost effective analysis. The results obtained for the stress and deflection within the study are corroboratory the analytically obtained results for all the cross-sections It was observed that with increase in length of beams, the stresses and deflections increases for flexural and combined loading but the behavior differs for torsional loading. The analysis shows the overall efficiency of the hollow rectangular section with bending stiffness laminate is higher than other laminated beams.