Seismic design approach for steel K-shaped eccentrically braced frames

This paper aims to propose a design approach for K-shaped Eccentrically Braced Frames (K-EBFs) according to the Theory of Plastic Mechanism Control in α−θ plane (TPMC(θ)). The novelty is the use of a new kinematic design parameter to avoid undesired collapse mechanisms, i.e. the plastic rotation θ of the dissipative members. Despite an increase of computational burden, with TPMC(θ) it is possible to obtain shallower column sections and, therefore, cheaper design solutions rather than those obtained by means of the original approach in the α−δ plane where the design parameter was the top sway displacement δ of the structure. The TPMC is an optimal design approach to overcome limitations due to the application of the simplified design criteria suggested by the code. It is based on a solid theoretical background and proposed as a design tool of seismic-resistant structures able to failure by exhibiting a collapse mechanism of global type. The design of several structures with different height is herein proposed, and the accuracy of the design procedure is validated through both pushover ad Incremental Dynamic Analyses (IDA) performed using natural records.