A genetic algorithm-based multi-objective optimization for hybrid fiber reinforced polymeric deck and cable system of cable-stayed bridges

As the length of main span of cable-stayed bridge increases, several technical challenges become more prevalent with traditional materials. Such technical challenges include: large axial stresses in main girders, cable sagging effect, and aerodynamic instability, consequently limiting the prospects of extending the span length of future cable-stayed bridges with traditional materials. In order to remedy these issues, we propose fiber reinforced polymeric (FRP) composites for the deck and cable system of cable-stayed bridges in combination with traditional materials. To use FRP composites most effectively, we developed a genetic algorithm (GA)-based optimization procedure to solve for the distribution of Glass FRP and concrete in the hybrid deck system, and the distribution of carbon FRP and steel in the hybrid cable system. This proposed optimization-based procedure aimed at developing two systems: (1) optimized hybrid Glass FRP-concrete deck system (OHDS), and (2) optimized Carbon FRP-steel cable system (OHCS), which can maximize static and aerodynamic performances concurrently. As an example, we utilized an existing long-span composite cable-stayed bridge and implemented these two systems. For a typical long span cable-stayed bridge, the results of this benchmark example provide insights about the typical composition of OHDS and OHCS and suggest that these two systems can concurrently improve the static and aerodynamic performances by 33 and 12 %, respectively.