Experimental evaluation of shear behavior of partially encased composite beams with replaceable bolted joints

This study proposes a Replaceable Bolted Joint (RBJ) for Partially Encased Composite (PEC) beams to enhance reusability and support efficient precast construction. Five PEC beam specimens were tested under monotonic shear loading to evaluate the effects of three parameters: the number of slits in the connection plate, the bolt type, and the shear-span-to-effective-depth ratio (a/d). Slitted connection plates increased peak load by about 11% through stress redistribution but reduced energy dissipation (45–68%) due to a smaller effective area. High-strength bolts provided approximately 13% higher peak load and stiffness than threaded rods. Increasing the a/d ratio shifted the response from brittle shear-dominated behavior to more ductile flexure-dominated behavior with smoother post-peak degradation, while strain measurements confirmed reduced local stress concentration and early shear yielding in specimens with smaller a/d ratios. These findings demonstrate that the proposed RBJ provides a viable design strategy for replaceable connections, contributing to resilient structural design and efficient modular construction practices.