Non Linear Shear Effects on the Cyclic Behaviour of RC Hollow Piers

Abstract

Reinforced concrete (RC) hollow section piers have been the subject of several studies in the recent past, from which one important drawn conclusion is the significant influence of shear effects on these piers behaviour, particularly under cyclic loading. In that framework, tests were carried out at Laboratory of Earthquake and Structural Engineering (LESE) from Faculty of Engineering of University of Porto (FEUP) on several reduced scale (1:4) RC hollow section bridge piers under lateral cyclic loading with constant axial force reported by Delgado (Bull Earthquake Eng 7:377−389, 2009). This work aims at presenting the numerical simulations performed for some of the referred piers in order to better understand phenomena associated with its cyclic behaviour, as observed in the experimental campaign. The numerical strategy was based on refined 3D Finite Element Mesh (FEM) discretization using a two-scalar variable damage model for the concrete constitutive law and a suitable cyclic behaviour law for steel bars represented by uniaxial elements. As is well known, the shear effects are complex phenomena involving the global behaviour of the structural elements and where the non linear effects have a crucial role. In this chapter a detailed modelling was used allowing for realistic simulations of the non linear behaviour, which was found particularly suitable when significant shear effects are involved. The bond between the bars and the embedding concrete, by incorporating a bond stress—slip behaviour law in the numerical calculations is considered, an effect particularly important when thin plain steel bars are considered, as is the case of the tested piers. The adopted formulation is similar to the well known Eligehausen proposals although with slightly modified cyclic behaviour parameters.