Is it safe to design a building structure with simple joints, when they are known to exhibit a semi-rigid behaviour?

It is shown, by means of computer simulations of the behaviour of a real structure, that it is safe to design a building with the assumption of pinned joints, even when they show a semi-rigid behaviour. This result is however limited to the cases where the joints show a high ductility, i.e. a capacity of large deformation before the rupture of either the bolts or the welds. Only in few, probably unrealistic cases, this assumption will lead to unsafe results, the lack of safety being however very small, amounting only to a few percent. (C) 2003 Elsevier Ltd. All rights reserved.