The objective of this study is to evaluate moment capacity based on interfacial shear stress of reinforced concrete (RC) beams strengthened with various types of fiber reinforced polymer (FRP) sheets. Toward this goal, RC beams strengthened with taper layered carbon FRP (CFRP) and hybrid FRP sheets were fabricated and subjected to four-point loading. From the experiments, interfacial shear stresses along the length of the CFRP sheets and maximum moments were obtained. The experimental results clearly showed that interfacial shear stress had significant influence on maximum moment of RC beams strengthened with FRP sheets. The relationship between interfacial shear stress and maximum moment capacity was considered for the moment capacity of RC beams with taper layered FRP sheets, and the numerical results showed good agreements with experimental results. In addition, finite element (FE) analytical studies were performed and the results validated relationship between interfacial shear stresses and maximum moment capacities. (C) 2015 Elsevier Ltd. All rights reserved.