Simplified calculation methods of flexural load-carrying capacity and deformation of prestressed concrete beams strengthened with U-shape steel plates

Based the experimental study and nonlinear analysis, the parameter numerical analysis were conducted to investigate the flexural performances of the prestressed reinfroced concrete (PRC) beams strengthened with U-shaped steel plates. The parameters, such as thickness of steel plate, heigth of the sided-plate, initial damage degree, and different level of effective prestressing were taken account to analyze their effect on the flexural strengthening. Based on some assumptions, the simplified calculation formulas of ultimate load-carrying capacity and flexural rigidity of PPC beams strengthened with U-shaped steel plates were proposed. The results indicate that the height of the sided-plate may not exceed one-third of the heigth of the beam. The increment of initial damage degree and the decrement of level of effective prestressing may not reduce the ultimate load-carrying capacity of the strengthened PPC beams obviously. The calculation results from the proposed formulas correlate very well with those from testing and ninlinear analysis.