The main objective of this study is to develop an analytical model to explain the behavior of a hybrid structure under different loading conditions. The model developed for a simply supported beam on moment capacity, stiffness, and deflection can be generalized to deal with any type of material combination. The dependence of moment capacity of the hybrid beam on the thickness of the composite sheet was investigated. The inherent property of a high Young's modulus and strain-to-failure properties of the composite material increased the moment capacity of the RC beam dramatically. The moment model showed a percentage increase of 284% for KFRP while on the other hand the percentage increases for CFRP and GFRP were 191% and 174% respectively when using a FRP sheet of thickness 0.025 mm. KFRP showed the highest increase in moment capacity because of its high strain-to-failure. CFRP on the other hand has a high Young's modulus, but its strain to failure is low, causing it to lie in the middle range. The analytical model is that the ability of a beam to handle moment is strongly dependent on the strength characteristics and the thickness of the FRP sheet.