Investigation of dynamic behavior of prestressed FRP plate intended for strengthening prestressed RC beam

•Developing an adequate analytical model based on the high order and the laminate theories to determine the free vibration characteristics of a prestressed composite plate.•Studying the effect the prestress effort on the free vibration characteristics.•Investigation of the effect of the fiber orientations on the free vibration characteristics. Strengthening concrete beams by prestressed or not prestressed composite plates has become one of the widely used techniques in civil engineering with the aim of improving the durability of infrastructures, specifically against seismic solicitations. However, this type of reinforcement is quite new for prestressed concrete beams. Before using a composite plate for strengthening prestressed concrete beams, it is important to know its dynamic characteristics. In this paper, an analytical model based on the high-order theory and the laminate theory is proposed in order to well determine the free vibration characteristics of presetressed composite plate. The presence of prestressing tension effort in the composite plate, which was not taken into consideration in earlier studies for slender composite plates, is the main innovation of the current research. Parametric studies varying prestressing effort and fiber orientations are carried out in aim to find the best way to use the composite plate in the reinforcing of prestressed concrete beams. For comparative purposes, a finite element model is carried out in order to explore the behavior of the composite plate under several boundary conditions (B.Cs). As an important result, this research reveals that prestressing effort stiffens the composite plate and makes it a strong choice for reinforcing prestressed concrete beams by increasing natural frequencies and reducing deflexion.