Seismic evaluation of eccentrically braced steel frames with heights under 100 meters using pushover analysis

Earthquakes are one of the primary considerations in structural design. The application of earthquake-resistant design has been increasingly implemented in recent years, particularly in steel structures. One such system is the Eccentrically Braced Frame (EBF), which is often selected by engineers due to its balanced combination of strength, ductility, and lateral stiffness. This study evaluates the structural performance level and ductility parameters of split-K type EBF systems used in office buildings with heights below 100 meters, specifically 48, 72, and 96 m. Nonlinear static (pushover) analysis was performed by modeling plastic hinges in the link beams and braces, in accordance with ASCE 41. Structural performance was evaluated using two assessment methods, Displacement Coefficient Method and Capacity Spectrum Method, under two seismic hazard levels: Design Basis Earthquake (DBE) and Maximum Considered Earthquake (MCE). The recalculation of ductility parameters, namely the overstrength factor (Ω0) and displacement ductility factor (µ), was based on FEMA P695 and carried out under the MCE level. The structural performance level evaluation results show that the 48 m building model achieved Life Safety (LS) under DBE and Collapse Prevention (CP) under MCE. The 72 m model achieved LS performance under both seismic levels, while the 96 m model achieved Immediate Occupancy (IO) under DBE and LS under MCE. All models satisfied the performance limits for new buildings as specified in ASCE 41. The recalculated values of Ω0 and µ exceeded the prescribed limits in SNI 1726:2019. Overall, EBF steel structures with heights below 100 meters remain acceptable in terms of seismic performance.