Pultruded GFRP Girders for the Replacement of Deteriorated Concrete Bridges

This paper investigates lightweight structural systems based on pultruded GFRP girders for the replacement of deteriorated concrete bridge decks on existing piers and abutments. The study is motivated by the need to rehabilitate short- and medium-span bridges affected by aging deterioration such as reinforcement corrosion. The approach preserves existing piers and foundations and, when required, enables rapid deployment for temporary or emergency applications. The proposed GFRP deck–girder solutions significantly reduce structural mass compared to conventional concrete systems. This reduction leads to lower seismic demand and smaller horizontal forces transmitted to the substructures. The research assesses the structural performance and feasibility of these systems, with particular attention to strength and serviceability behavior. The objective is to identify solutions that can be replicated across different bridge configurations, while also outlining efficient strategies for onsite assembly. After a reasoned review of the solutions available in the literature and of the limitations related to deformability, strength, and instability for a preliminary analytical design approach, three-dimensional numerical simulations of GFRP bridge deck systems are performed to evaluate global behavior and load-transfer mechanisms. The latest design codes and guidelines for GFRP bridges are reviewed and applied. Based on the results, recommendations are provided regarding cross-sectional proportions and member slenderness. The numerical results are compared with the analytical design approach, showing that, under characteristic load combinations, maximum deflections can be limited to approximately L/300–L/400 when the beam depth-to-span ratio range is between 1/10 and 1/6. Within these relationships, spans between 10 m and 25 m are found to be efficient. Additional guidance is proposed for modular construction strategies based on standardized pultruded elements and factory-controlled bonded connections.