SULLA VARIABILITÀ DEL MODULO ELASTICO NELL’ACCIAIO STRUTTURALE

Design of steel structures is frequently carried out in elastic range, considering eventually the influence of the deformations (i.e. transversal displacements or, equivalently, second order effects) for members and/or components that are flexible. The value of the elastic modulus, E, is of paramount importance of the whole design path but it is always assumed as a deterministic data, independently by the considered design approach. Standard provisions for the characterization of the structural steel grades require ladle and product chemical analyses and mechanical tests to evaluate the main mechanical properties but do not impose the evaluation of E. In the past, in Italy as well as in other countries, E for the structural steel was considered equal to 206GPa. Now, standard provisions recommend E=210GPa, as in all the Europe. The present paper summarizes an analysis carried out on the variability of the elastic modulus for steel grades currently used for structural applications. The considered data derives from both the results published in several peer-review papers and from technical report on material tests. Research outcomes stress out a relevant and unexpected dispersion in the E distribution, suggesting the need of standard requirements imposing the E evaluation, at least for the in-situ material checks, especially if load tests are planned for the final testing phase.