Flat Slab–Column Modeling Using Finite Element with Eccentric Loading Effects

Abstract

Slab–Column connection is one of the critical structural joints in building construction, since there are special design requirements that must be achieved. This paper investigates RC slab–column connections under eccentric load using a built-in 3-Dimensional Nonlinear program of finite element in the pre- and post-cracking levels and up to the ultimate load. The concrete is simulated as isoparametric brick element, and the reinforcement bar elements are assumed to be built into isoparametric brick elements. With regard to load–deflection responses and ultimate strength capacity, a good coincidence is achieved for FEA and experimental results with maximum difference 1.6% for ultimate strength. In addition, the structural performance investigation of slab–column connection is carried in terms of the effectiveness of applied load types, shear reinforcement and slab thickness. It can be concluded that the increase in loading eccentricity cause decreasing in ultimate load 20.5 to 40% in comparison with case of e = 0, which is one of conclusion of this research. Also, the use of shear reinforcement (48 stirrups of Φ10 mm) in the flat slab connection with columns had more effects than slab depth. It is found that the ultimate load capacity increases about 34.4% with e = 0.0, while it decreases about 22% with e = 0.45 m when compared with slab–column connections without shear reinforcement (e = 0.0). In addition, as the slab thickness increases from 150 to 200 mm, the ultimate load increases about (25%) when compared with case of (e = 0.0), while the ultimate load increases about (2.3%) when compared with the same case of (e = 0.0), which means that the increment in the slab thickness can be considered as compensation for the effects of increasing in load eccentricity. Also, for the slab–column connection without shear reinforcement, the related formula of ACI-code gives a good agreement in terms of ultimate load capacity in comparison with the results of adopted FE model with maximum difference 4% as the unbalanced moment was increased, while for usage of shear reinforcement in slab–column connection, the formula of ACI-code becomes more conservative with maximum difference 10% with increasing of unbalanced moment.