Seismic performance optimization analysis of HPEC beam to H-section column joints

To fully exploit the advantages of steel-concrete composite structures and reduce material consumption and self-weight, this study proposes a novel prefabricated hollow-core partially encased composite beam (HPEC)-to-H-section column joint (PHHJ); however, its seismic performance and key detailing effects remain insufficiently understood. Six 1/2-scale specimens were tested under low-cycle reversed loading to evaluate the effects of hollow ratio, stiffener length, and cover plate length on failure mode, hysteretic behavior, energy dissipation, and ductility. Refined ABAQUS models were validated and used for parametric analyses of stiffener position, widened flange, and connection form. The primary failure modes were flexural failure and connection failure. The hysteretic curves exhibited a shuttle shape with good energy dissipation, and the maximum equivalent viscous damping coefficient reached 0.24. Initial stiffness degradation was mainly caused by buckling of the H-section steel beam flange, whereas later degradation was governed by steel yielding and concrete crushing. The maximum ductility coefficient was 1.61. Bearing capacity was relatively insensitive to stiffener length, cover plate length, and hollow ratio, and its degradation mainly depended on damage to reinforced concrete in the filling area. FEM results show that stiffeners relocate the plastic hinge away from the column face, while a widened flange alleviates stress concentration at the interface between the HPEC flange edge and the beam end plate. A connection combining stiffeners and a widened flange is recommended, with stiffener length > 200 mm, widened flange width matching the column flange width, and length ≥ 200 mm. These findings provide a reference for the seismic design and engineering application of HPEC beam-column joints.