Closed Form Design Equations for Strengthened Concrete Beams: FRP Rupture

Synopsis: Externally bonded FRP has been established as the technology of choice to strengthen RC beams. Researchers and practicing engineers have recently developed design guidelines for FRP strengthening. However, the current state of the art flexural design procedure suggests an iterative process. No earlier efforts have been devoted to develop direct strength design equations on the failure mode of FRP rupture that can facilitate structural calculations. This study develops exact and approximate sets of closed form equations to design singly and doubly reinforced strengthened rectangular sections that fail by FRP rupture. Comparisons with reported experimental strength data indicate excellent agreement. A comprehensive parametric study has yielded a simple linear regression equation that has an almost perfect statistical correlation and is equally applicable in cases of analysis and design. Comparison between the exact solution and the regression equation confirms the accuracy of the latter. The latter is used in a design example.