Cyclic behavior of composite beam–steel column joints with peripheral laminated slabs

This study introduces a novel laminated flooring system featuring narrow wet joints for frame connectivity, which significantly improves the assembly efficiency. Cyclic loading tests on four composite joint specimens were conducted to systematically evaluate the effects of width and material type of wet joints on the seismic performance. The results revealed that the specimens with C35 wet joints exhibited comparable seismic behavior to that with cast-in-situ slabs, with less than 5 % deviation in energy dissipation, load-bearing capacity, and stiffness degradation, attributed to similar crack propagation and consistent failure modes (concrete crushing around columns). Besides, the mechanical performance of composite joints was insensitive to the width of wet joints. The low damage characteristic of ultra-high-performance concrete (UHPC) wet joints reduced the energy dissipation capacity of the composite joint by about 16 %, but the well-maintained interaction between UHPC and columns significantly improved the secant stiffness by over 40 % and load-bearing capacity by 29.20 % at peak state. Moreover, strain-based analysis quantified the development of effective flange width at composite beam ends, and the calculated load-bearing capacity highlighted the tensile contribution of UHPC. Finally, the refined finite element model revealed the effect of experimental parameters on the deformation characteristics of five critical components governing the overall deformation of composite joints. The proposed system provides an innovative solution for industrialized development of prefabricated floor systems while offering new perspectives for enhancing seismic performance of composite joints through UHPC applications.