Theoretical Study on the Behavior of Interfacial Slip and Deflection of the Steel–Concrete Composite Beam

This study introduces a theoretical model that comprises two individual Euler beams interconnected by interfacial continuous springs to investigate the performance of steel–concrete composite beams (SCCBs). The differential element method and the principle of minimum potential energy were employed to ascertain the interfacial slip and deflection based on the proposed model. Finite element (FE) analyses of simply supported and two-span continuous beams were conducted to verify the model's accuracy. Additionally, a parametric study was carried out to examine the influence of stud arrangement, stud diameter, and concrete strength on the behavior of SCCBs. The findings indicate that: (1) the theoretical interfacial slip and deflection closely matched the data from the FE model, exhibiting low variations while the composite beam operated in the elastic stage; (2) stud arrangement had a negligible impact on the behavior of SCCBs with a constant shear connection; (3) an increase in stud diameter significantly improved sectional stiffness, leading to reductions in slip and deflection of 52.6% and 11.6% as the diameter increased from 8 to 16 mm; (4) an increase in concrete strength from 30 to 80 MPa resulted in a limited impact, reducing slip and deflection by 17% and 6%, respectively.