Analysis and design of long-term responses of simply-supported steel–concrete composite slabs

Abstract

Steel–concrete composite slabs have several advantages such as fast construction and a high degree of industrialization. Due to the sealing effect of profiled steel sheets (leading to the non-uniform shrinkage through the thickness of concrete), the composite slabs exhibit an additional deflection. At present, most design formulas for calculating the long-term deflection of composite slabs have ignored the effect of non-uniform shrinkage, while some other methods usually have complex procedures when considering the effect of non-uniform shrinkage. Furthermore, the influence of non-uniform shrinkage on the stress on the profiled steel sheet of composite slabs has not been studied to date. In this manner, this paper establishes a finite element model (FEM) of simply-supported composite slabs while considering the impacts of the non-uniform shrinkage, cracking in the concrete, and the creep of the concrete; then, the reliability of the FEM is verified against the experimental data in the literature. Next, a systematic parameter analysis is conducted to study the influence of the non-uniform shrinkage on the deflection of the composite slabs and on the stress on the profiled steel sheet; the key influencing factors are also determined. We then propose a new simple formula for calculating the deflection of the composite slabs by considering the effect of the non-uniform shrinkage; another equation is also developed for determining the stress on the profiled steel sheet. The results show that the non-uniform shrinkage has a significant impact on the long-term performance of the composite slabs. In particular, the non-uniform shrinkage increases the long-term deflection of the composite slabs by 37–285% and enlarges the stress on the profiled steel sheets by 65–98%. The proposed calculation formula is in good agreement with the FEM. The average ratio of the results predicted by the calculation formula to those computed by the FEM is in the range of 1.004–1.044, and the coefficient of determination (R2) ranges from 0.811 to 0.828.