Optimum Design of RC Beams Strengthened with Externally Bonded FRP Using Pattern Search

This paper discusses the efficiency of using the Pattern Search (PS) tool to optimize the design of RC beams strengthened with externally bonded (EB) fiber-reinforced polymer (FRP) materials. The study considers shear strengthening (three-sided or two-sided configurations), flexure strengthening, and coupled shear-flexure strengthening. The design process involved an objective function that represents the cost function of the optimum solution and design variables that define the optimum dimensions of the beam and FRP material, such as beam width, effective beam depth, FRP strip thickness, FRP strips spacing, and FRP strip width, according to the design constraints of the ACI 440-2R-17 code. To achieve the goal of this paper, different examples were conducted under shear, flexure, and coupled shear-flexure strengthening. In each case, the PS technique resulted in more compact designs with a faster convergence rate, reducing costs compared to the original dimensions of the design variables. In this context, an extensive parametric study was conducted to determine the ability to redesign the FRP material dimensions compared to previously published data. The results showed that the pattern search technique could save costs in designing RC beams strengthened with externally bonded FRP under similar loading conditions.