Numerical Study on the Performance and Failure Modes of Bolted Connections in Pultruded-Fibre-Reinforced Polymer (PFRP) Profiles

The use of pultruded-fibre-reinforced polymer (PFRP) composite profiles in structural applications is rapidly increasing, due to their high strength-to-weight ratio, corrosion resistance, and durability. Bolted joints between PFRP play a critical role, as localized high stresses in a material that typically exhibits brittle behaviour—especially in tension and shear—can lead to sudden failure. This study aims to investigate the mechanical performance of such bolted connections (in terms of stiffness, strength, displacement capacities and failure modes), contributing to the development of reliable yet optimized design criteria for structural applications. In particular, numerical analyses of single-bolted connections in PFRP profiles are presented in the paper. To emphasize the general validity of the model and demonstrate its applicability across different configurations, the simulations were validated against experimental results from three separate test campaigns, which varied in both material (three different PFRP composites) and geometry (profile thickness, bolt diameter, and hole–end distance). Finite element models using continuum shell elements in ABAQUS, based on the Hashin failure criteria, successfully captured typical failure modes, including shear-out and pin-bearing. Two analysis approaches—implicit and explicit solvers—were also compared and discussed. Sensitivity analyses were carried out to enhance the model’s accuracy and its computational efficiency. The validated model was then extended to simulate different configurations, investigating the role of the main parameters influencing the connections.