Modelling for Design

Abstract

In several current aseismic codes, the design of structures takes into account the so-called behavior factor, that is an estimator of the structure’s ability to undergo large post-yield cyclic deformations with an acceptable, relatively small reduction of its bearing capacity. Under given conditions of redundancy and regularity the behavior factor assumed in design can be translated into required curvature ductility factors at the section level [4.1], which are normally ensured by adequate layout and sufficient quantity of transverse confining reinforcement (closed hoops). Herein, a model is presented for the calculation of the required transverse reinforcement of columns to achieve a given curvature ductility, μ _1/r . In this model, the required transverse reinforcement is related to the main parameters that influence the curvature ductility, namely the normalized axial force, ν _d , the mechanical characteristics of the materials, the transverse reinforcement arrangement, as well as the ratio between the column’s gross cross-sectional area A _c and its confined part, A _o .