Some considerations about the eurocode 8 R.C. frame building assessment procedure

In the European seismic countries, the seismic assessment of existing structures is a priority, since the majority of the building heritage was designed according to out-of-date or even no seismic codes. The uncertainties about the nonlinear behaviour may be relevant, since the potential development and location of inelastic zones, as well as their ductility capacity, are, in general, unknown. The direct consequence is that the nonlinear response should be faced directly, with corresponding strong increase of the complexity of the assessment process. This issue was taken into account in this work; in particular, four R.C. frame buildings, all irregular and characterized by different geometric and material properties, were selected and assessed according to all the possible methods proposed in Eurocode 8 (EN 1998-3), with the following aims: i) suggesting simplified approaches and improvements for the assessment procedure, concerning the evaluation of both seismic demand and capacity of the structural members; ii) suggesting the most appropriate definition of the effective stiffness in linear analyses.