Experimental study on moment redistribution of two-span continuous beams with bolted plate connections

This study presents an experimental investigation into the flexural behavior and moment redistribution capacity of precast two-span continuous concrete beams with bolted steel plate connections (PCBBSCs). A total of eight full-scale specimens were tested, including seven PCBBSC beams and one monolithic cast-in-place control beam (CCB-B). The PCBBSC beams featured a deliberate discontinuity at the middle support (hogging zone), where precast segments were mechanically spliced using U-shaped steel plates, high-strength bolts (M16 and M8), and structural epoxy adhesive. The main variables investigated were the hogging-to-sagging reinforcement ratio (0.80 and 1.00) and the steel plate thickness (2.0–3.5 mm). All beams had a total length of 6000 mm, with cross-sectional dimensions of 150 mm × 250 mm, and were subjected to monotonic loading at both midspans. Results showed that bolted connections ensured load continuity and enabled stable flexural behavior. Moment redistribution was quantified using support reaction measurements and was found to evolve from an initial elastic distribution to post-yield reallocation, remaining within code-permitted limits. A three-plastic hinge mechanism was observed in in beams utilizing the equivalent design thickness (two at sagging and one at hogging, with fracture or partial separation of the steel plate). While beams with the overstrength thickness of steel plates exhibited a different hinge formation, with one or two plastic hinges developing near the ends of the steel plate in the hogging region. The PCBBSC beams exhibited ductile performance and high deformation capacity, comparable to the monolithic specimen. The findings demonstrate that a well-chosen thickness of bolted steel plate connections can reliably sustain continuity effects in precast continuous concrete beams.