Rapid growth in population and urbanization have led to the expansion of construction activities to challenging locations with difficult subsurface conditions such as hills, sand, and water. Building in these areas requires both strong engineering skills and quality control. The scarcity of flat land and the increasing population have driven the construction of buildings on slopes in hilly regions. Unlike buildings on flat land, buildings in hilly areas typically follow the natural slope of the ground for support and exhibit unique structural configurations, namely step back (SB) and split foundations (SF). However, past earthquakes, such as the Sikkim earthquake in 2011, have demonstrated that buildings with these configurations, even if constructed with reinforced concrete (RC) following code guidelines, are prone to severe damage. Torsional irregularities arise due to the presence of short columns at intermediate stories, and substandard construction quality further exacerbates their vulnerability to seismic action. Consequently, the seismic losses for buildings in hilly areas are expected to differ significantly from those for buildings on flat land. This study focuses on estimating the seismic losses associated with the structural components of nine RC building models designed according to recent Indian code recommendations. Nonlinear response history analysis is conducted to determine the peak seismic response in terms of interstory drift ratio (IDR), an important engineering demand parameter (EDP) for seismic loss estimation. The seismic repair losses corresponding to the structural components are estimated using the performance-based earthquake engineering framework provided by the Pacific Earthquake Engineering Research (PEER) center. The analysis reveals that the pattern of story drift and peak floor acceleration in hilly buildings is non-uniform, characterized by sudden peaks at one or two levels depending on the foundation arrangements. As a result, the expected losses due to structural component damage at various floor levels significantly differ between typical buildings in hilly regions and those on flat land.

Hilly Building; Interstory Drift Ratio; Loss Estimation.