Improved earthquake resistant design of eccentric steel buildings

Recently, a design modification has been proposed for eccentric, torsionally stiff, braced steel buildings, designed according to the current Eurocodes 3 and 8, that improves noticeably their inelastic response under the action of design level earthquakes. The improvement consists in a more uniform distribution of ductility demands throughout the building. In the present paper, a similar, though differently derived, modification is applied to torsionally flexible eccentric buildings and their response is again evaluated under pairs of design earthquake motions. A substantial improvement of their inelastic response is also observed, similar to what had been obtained for torsionally stiff buildings. The new approach is also tested with torsionally stiff buildings and leads to similarly satisfactory results. Thus it may be recommended for general application.

► It studies the inelastic earthquake response of eccentric, braced steel buildings.
► Original asymmetric buildings were designed according to EN 1993, 1998.
► Great differences in ductility demands on opposite edges under design earthquakes.
► A design modification is proposed reducing differences in ductility demands.
► Modified buildings meet code requirements. A code modification appears desirable.