Effective width evaluation for HSS-UHPC composite beams with perfobond strip connectors

This paper investigates the design criteria for predicting the effective width in high strength steel (HSS)-to-Ultra-high performance concrete (UHPC) composite beams with perfobond strip connectors (PBLs). Twenty-eight HSS-UHPC composite beams with varying parameters of shear connection degree (C), span length (S), thickness (T) and width (W) of UHPC slab were numerically simulated and evaluated. The composite beams' strain distribution and shear lag effect were presented and analyzed. Results indicate that the shear lag of the HSS-UHPC composite beam under flexural loadings was significant, and the effective width coefficient (β) of the concrete slab was enlarged by the magnification of the C, T, and S. A comparison between the results obtained from the FE model and procedures for predicting the composite beams’ effective width was performed to assess the feasibility of design approaches. It reveals that existing codes provide good predictions for the HSS-UHPC composite beams with a W/S ratio below 0.3 but underestimate the effective width for those with W/S ratio beyond 0.3. Furthermore, an empirical model for predicting the effective width of HSS-UHPC composite beams, considering the shear lag and steel-to-UHPC interfacial slip, is derived and fitted by a data regression. The outcome of this study can provide a reference for HSS-UHPC composite beams in practical applications.