The master thesis focuses of the design of a 5-storey steel building composed of Moment Resisting Frames (MRFs), with an emphasis on the efficient dissipation of seismic energy in joints equipped with friction dampers. The sesmic design of the MRFs is carried out according to the rules of the new draft Eurocode 8, taking into account the requirements in the Significant Damage (SD) limit state for ductility classes DC2 and DC3. The essential change in the new version of Eurocode 8 is the definition of the elastic response spectrum, which is determined by two different procedures. It has been found that the values of the spectral accelerations at the plateau are higher compared to the current standard. Moreover, in the range of medium and long vibration periods, the response spectrum depends on the chosen seismic action procedure. Significant changes to the new standard include the definition of new ductility classes, limit states, behaviour factor and interstory drift sensitivity coefficient in the control of second-order effects, together with new limitations of interstorey drift at SD. The seismic analysis of MRFs is carried out using planar computational models for three different seismic scenarios, where the seismic impact is defined by the lateral force method. In the case where the seismic action has been determined according to the new Eurocode 8 with respect to the first method, when the spectral accelerations are known, a lighter structure with smaller cross-sections of the elements has been obtained. When designing MRFs, it turns out that the control of interstorey drifts is the key issue, and no longer control of second-order effetcs. The design of innovative joints with friction dampers, which dissipate seismic energy without damage, is carried out in accordance with the FREEDAM PLUS document, which is an addendum to the new standard.