Proposal of modifications to the design provisions of Eurocode 8 for buildings with split K eccentric braces

• Some modifications are proposed to the design procedure suggested in EC8.
• The effectiveness of EC8 procedure is compared to that of the proposed procedure.
• A simple relation for the evaluation of the behaviour factor is proposed.
• Restrictions to the use of the lateral force method of analysis are suggested.
• The rules for the strength required to counteract P–Δ effects are discussed.

This paper evaluates the effectiveness of the procedure suggested in Eurocode 8 for the design of eccentrically braced structures and compares the seismic response of buildings designed according to this procedure to the response of buildings designed according to the modifications proposed by the Authors. The proposed procedure modifies that of Eurocode 8 in order to fill gaps and make the new procedure consistent with the intent of the code. The seismic response of the buildings is obtained by incremental dynamic analysis. To ensure the general validity of the results, the buildings are considered to be founded on hard or soft soil and are characterised by different values of the link length and number of storeys.