Experimental and numerical study of shear-lag effect on low-ribbed steel-UHPC composite structure

Due to its excellent mechanical properties, the application of Ultra-High Performance Concrete (UHPC) in the field of civil engineering is rapidly increasing. Recently, a UHPC-based composite structure referred to as a low-ribbed slab steel-UHPC composite beam (SUHPC-LRSCS) is developed, which can reduce the structural self-weight significantly without compromising the mechanical performance of the structure. Because the shear-lag effect (non-uniform stress distribution) tends to cause localized damage to the structure, it is critical to consider this effect on the relatively new composite structure. In this paper, it numerically demonstrates that the shear-lag effect on this low-ribbed composite structure is greater than that of the composite beam with a traditional rectangular cross-section. To avoid the inaccuracy analysis in the structural design, this paper proposes a theoretical calculation approach for considering the shear-lag effect on that based on the bar simulation method. The effectiveness of the proposed method is verified by both the lab experiment and FE models. The proposed method presents high accuracy results showing a potential application in the engineering field. In addition, for the proposed method, the effects on both the determination of the bars quantity and separation ways for calculating the bar equivalent area are investigated. Finally, a suggested upper limit of the shear-lag coefficient for simply supported SUHPC-LRSCS is given for reference.