A compact finite element model for N.L. analysis of concrete structures

A comprehensive very compact finite element is proposed, able to describe the behaviour of 2D concrete structures from serviceability conditions up to the collapse. The formulation of this finite element is derived from a resistant criterion based on a plasticity theory approach, in which the deviation Δθ between the angle of first cracking and the compressed stress field at failure is the main key parameter to describe the structural behaviour. In practice the evolution of damage in the compressed concrete stress field is related to Δθ for every load step and increasing action level. The robustness of this finite element may be found in its compactness and then in the reduction of the number of input parameters, that are often difficult to define properly and may govern in a sensitive measure the structural response. The proposed F.E. is then used to reproduce some well know experimental tests, both on elementary panels and more complex 2D structures, showing a satisfactory capability to predict the 2D reinforced concrete structural behaviour.