Seismic Performance and Fragility Assessment of RC Frame Buildings Equipped with Yielding Brace Systems Using NSPA and IDA

Structural engineers aim to achieve the highest level of structural safety, particularly in earthquake-prone areas. Recent earthquakes have highlighted the urgent need for resilient engineering solutions. Given India’s high earthquake risk, especially in the northeastern and Himalayan regions, there is an increased emphasis on advanced seismic protection systems. This study focuses on the yielding brace systems (YBS), a seismic energy dissipater that improves structural resilience by dissipating energy during earthquakes. Unlike traditional braces that can buckle under compression, the YBS provides stable, nonlinear behavior in both compression and tension during an earthquake. This stability is due to the yielding fingers connected through a cast steel connector. In India, most buildings are constructed as low- to mid-rise structures. To evaluate the YBS performance in buildings of varying heights, this study examines three plan-symmetric RC frames of 6, 9, and 12 stories. The research uses nonlinear static pushover analysis (NSPA) and incremental dynamic analysis (IDA) to assess seismic performance, aiming to restrict building damage to 1%–2% of the target drift. Seismic fragility analysis reveals that incorporating YBS significantly enhances seismic resilience, reducing the probability of collapse by 20%–30% in 6-story buildings, 25%–35% in 9-story buildings, and 30%–40% in 12-story buildings. Increasing YBS implementation to 2% further improves these reductions, demonstrating the system’s effectiveness in enhancing structural stability and performance under seismic conditions.