Structural behavior of steel-concrete-steel sandwich slender and deep beams considering different connectors

Steel-concrete-steel (SCS) sandwich deep beams, with a shear span ratio of less than 2.0, are commonly employed in high-rise buildings and bridges. However, their failure mechanism differs from that of SCS sandwich slender beams, which have a shear span ratio greater than 2.0. This study systematically investigates the failure mechanisms of SCS sandwich deep beams and compares them with those of SCS sandwich slender beams. To improve their structural performance, ultra-high performance concrete (UHPC) was utilized as the core material to form S-UHPC-S sandwich deep beams, with shear studs serving as the sole shear connectors. The influence of these shear connectors was explored in comparison to cross ties. Three S-UHPC-S sandwich deep beams were subjected to static loading, and their performance was compared with ten existing SCS sandwich deep and slender beams. The analysis focused on failure modes, mechanical behaviors, and contributions of each component, including the steel plate (SP), core concrete (CC), and shear connectors. The results revealed distinctions in force transferring models, load-displacement curves, and the contributions of cross ties in deep beams compared to slender beams. Additionally, finite element (FE) analyses were employed to examine the force transferring mechanism of shear connectors. Based on both experimental and FE simulation analyses, theoretical models for predicting the ultimate capacity of S-UHPC-S sandwich deep beams and slender beams were proposed, accounting for different shear connectors. These models offer valuable insights for practical structural design and application.