Numerical analysis and experimental validation of new steel-stiffened hybrid steel-PFRP bolted joints

A new hybrid steel-PFRP (Pultruded Fiber-Reinforced Polymer) bolted joint stiffened by steel plates is proposed in this paper to improve the joint efficiency for hybrid steel-PFRP lattice structures. The performance of the new steel-stiffened hybrid steel-PFRP joint (SHJ) was investigated and compared with that of ordinary steel-PFRP bolted joint (OBJ) using finite element method (FEM) and experimental test. In the numerical simulations, three-dimensional (3D) progressive damage joint models were developed and validated by joint tests, in which damage was investigated by employing Hashin failure criterion for PFRP part. Moreover, full-scale structural tests were also performed to further calibrate the performance of SHJ and OBJ in hybrid steel-PFRP lattice structures. The results from both joint level and structure level indicate that the performance of SHJ including ultimate bearing capacity, stiffness and joint efficiency is prominently superior to that of OBJ. SHJ is feasible and effective for application in hybrid steel-PFRP lattice structures. Parametric studies on SHJ were further conducted. The influences of the geometric parameters, such as the end distance to bolt diameter ratio (e/d) and the PFRP width to bolt diameter ratio (w/d), on the failure mode of SHJ were also discussed with the validated 3D progressive damage models.