Enhancing seismic design in high-hazard zones: Code gaps and recommended revisions

Current seismic design codes adopt a life-safety philosophy based on probabilistic seismic hazard models with return periods of 50–100 years. This approach accepts significant structural and nonstructural damage under major earthquakes, relying heavily on high ductility demands and seismic force reduction factors (R-factors). However, recent earthquake events in high-seismicity regions—particularly Turkey—reveal the inadequacy of these assumptions, as many newly constructed buildings have suffered severe damage or collapse within less than five years of service. Additionally, nonstructural elements such as brittle brick partition walls continue to cause life-threatening hazards despite structural stability. This paper examines critical gaps in existing seismic codes related to (1) the use of brittle partition walls, (2) insufficient structural damping requirements for high-occupancy buildings, and (3) over-reliance on large R-factors that significantly reduce design base shear. Based on observed earthquake performance, field reconnaissance, and analytical understanding of structural dynamics, the paper proposes three new code provisions: (a) restriction of brittle masonry partitions in high-seismic zones, (b) mandatory supplemental damping of at least 15% of critical damping in buildings with high occupancy, and (c) reduction of R-factors to improve structural integrity and post-earthquake functionality. These revisions aim to shift the seismic design philosophy toward resilience, continuity of function, and long-term safety.