Reliability analysis of non-linear reinforced concrete frames using the response surface method

In this paper, a formulation to compute the reliability of reinforced concrete structures, in which physical and geometrical non-linearities are taken into account, is described. The adopted non-linear model allows the representation of the mechanical behaviour of concrete structures at the failure stage, which is governed by possible large displacement effects, softening behaviour of concrete and tension stiffening effects. On the other hand, the reliability model is based on adaptive failure surfaces representing the mechanical model responses. The failure surface is obtained by fitting the internal force ultimate state of the structure using a quadratic polynomial. The structural reliability index is estimated by the Rackwitz and Fiessler algorithm, which has shown to converge after a reduced amount of iterations. A parametric numerical analysis of columns and frames is presented for practical applications, where the partial safety factors proposed by international codes of practice are associated with reliability indexes.