Eurocode‐8‐conforming seismic design and behaviour factor of high‐post‐yield stiffness concentrically‐braced steel frames

Abstract A seismic‐resistant steel frame with energy‐dissipating, chevron‐type braces is proposed. The braces are equipped with replaceable hourglass‐shaped pins made of duplex stainless steel. Under design seismic loading, energy is dissipated through inelastic deformations confined in the replaceable pins while the other members remain essentially elastic. As a result, the frame exhibits high post‐yield stiffness due to the inherent properties of the stainless‐steel pins. A Eurocode‐8‐based design methodology is adopted for the frame and assessed following the Eurocode‐8‐compatible INNOSEIS approach. Specifically, the overstrength factor is evaluated through nonlinear pushover analysis while the behaviour factor is assessed through incremental dynamic analysis considering high and medium seismicity site‐specific ground motion suites. The determined behaviour factor satisfies the global collapse prevention and life safety objectives while also keeping the maximum residual inter‐storey drifts below 1/300 to permit an easy substitution of the damaged pins after the design level earthquake.