Historical Evolution of IS 1893 Base Shear Provisions: Towards a Novel Approach in the 2025 Code Revision
Vrushali Kamalakar, Chenna Rajaram · Journal of Earthquake Engineering · 2026
The Indian seismic code IS 1893 evolved through a continuous process driven by seismological advancements, structural engineering progress, and past earthquake lessons. The current study examines IS 1893’s historical development, focusing on base shear calculation changes and structural design implications. The base shear computations are done across past revisions of the code and the study evaluates representative low-rise (G+3), mid-rise (G+7), and high-rise (G+15) buildings across seismic zones and site classes. The latest IS 1893:2025 revision introduces a comprehensive, scientifically robust approach incorporating Probabilistic Seismic Hazard Assessment (PSHA) methodologies. The results reveal that the base shear is increased to 30% in the Working Stress Method (WSM) compared to IS 1893:2002 or 2016, while the base shear rises by 1.8 to 3.2 times in higher seismic zones. The key findings emphasize adopting current code provisions, retrofitting older structures, and considering the environmental impacts of seismic design decisions. The code’s evolution demonstrates India’s commitment to enhance seismic safety standards while aligning with global best practices in structural design, ensuring progressively safer built environments.