New Seismic Design Provisions in BNBC-2020: A Quick Appraisal

The updated Bangladesh national building code (legally enacted as BNBC-2020) contains new seismic design provisions including a new seismic zoning map dividing the country into four seismic zones with seismic zone coefficients varying from 0.12 to 0.36. This paper briefly explains the salient features and significance of these provisions which were finalized way back in 2010. Since then there have been new developments and new research in the field of seismological research and earthquake engineering. A general appraisal is done on some of the important code provisions related to seismic loads through brief comparison with other building codes and research publications both new and old. Several seismic hazard assessment studies, both probabilistic and deterministic, have been conducted for Bangladesh adopting different procedures. Particular reference will also be made to a recent publication indicating the possibility of a mega earthquake (magnitude 8.2–9.0) deep inside Bangladesh. Bangladesh is located at a complex seismo-tectonic regime close to the plate boundaries of Indian plate and Eurasian plate in the north as well as plate boundaries of Indian plate and Burmese sub-plate in the east. It is emphasized that it is indeed a great challenge to conduct seismic hazard assessment of Bangladesh and several years of coordinated seismological research work needs to be carried out for a realistic assessment.