Seismic performance assessment of eccentrically braced steel frames with energy-absorbing links under sequential earthquakes

Recent studies have indicated the need of considering aftershocks in the seismic design/assessment of structures. This article investigates the effect of sequential mainshock and aftershock earthquakes on eccentrically braced steel frames with vertical energy-absorbing links. To achieve this, 4, 8 and 12-storey frame buildings are modelled in Perform3D (R) software considering non-linear behaviour of materials and components. The frames are subjected to a set of 12 main earthquake records corresponding to the required hazard level, and then subsequent aftershocks are applied using incremental dynamic analysis (IDA). To reduce the computational cost, an alternative approach is also adopted by applying the main earthquakes to the system followed by pushover analyses on the damaged building assuming a lateral load distribution proportional to the shape of the first vibration mode. Subsequently, the fragility curves are obtained for different damage levels, before and after the main earthquake. The results show that the eccentric braced frames with vertical links subjected to sequential earthquakes comply well with the performance levels of the Iranian Seismic Code. This study contributes toward the assessment and seismic validation of structures with eccentrically braced steel frames with vertical energyabsorbing links to sequential earthquakes.

Automated summary

Recent studies have shown the importance of considering aftershocks in the seismic design of structures. This article specifically investigates the impact of sequential mainshock and aftershock earthquakes on eccentrically braced steel frames with vertical energy-absorbing links. The results demonstrate that these structures meet the performance levels outlined in the Iranian Seismic Code in response to sequential earthquakes.