Effects of pulse-type near-fault ground motions on the nonlinear seismic response of steel frames with inverted-V CBF and EBF systems

The type of lateral load-resisting system plays a critical role in controlling the seismic response of steel structures subjected to strong ground motions. In this research, the structural performance of three-dimensional (3D) steel buildings designed with concentrically braced frames (CBFs) and eccentrically braced frames (EBFs) under near-fault ground excitations (NFGEs). A 3D steel building with dual bracing systems, including inverted-V-shaped EBFs and CBFs, were designed under the influence of NFGE. The response of 4 and 8-story structures subjected to NFGE was assessed using nonlinear time history analyses (NTHAs), which were categorized into small-pulse (SP), medium-pulse (MP), and large-pulse (LP) scenarios. This research aims to assess how pulse characteristics affect lateral story and inter-story displacements in buildings of different heights, as these displacement demands are critical indicators of seismic performance and structural strength degradation. This study provides a systematic evaluation of the seismic response of low- and mid-rise CBF and EBF systems under different pulse-type near-fault ground motions, highlighting the role of lateral story displacements as a key performance indicator. The results demonstrate that seismic performance is highly dependent on building height and pulse characteristics, with EBFs showing superior performance in mid-rise buildings under medium-pulse excitations, while CBFs are more effective in low-rise structures, emphasizing the need for height- and pulse-specific bracing strategies.