Reconnaissance of Buildings Impacted by the 2018 Tornadoes in Ottawa, Canada

Abstract

On September 21, 2018, two major tornadoes occurred in Ottawa, Canada. The most severe was an Enhanced Fujita (EF3) storm that happened in Dunrobin area. The second major storm took place in the Arlington Woods area and was an EF2 tornado. These severe events destroyed numerous buildings, and thus a field investigation was conducted to observe the damages in the structures. The survey included both low-rise commercial and residential buildings in the Dunrobin and Arlington Woods areas; in the first area many buildings experienced extensive damage and in many cases local collapse, whereas in the second area the damage was limited on garages and roofs. The paper presents a set of damage-assessment data with a focus on damage failure modes and functionality of the buildings during the inspection. Lessons learned from the damages are finally presented, with comparisons with evidence from past tornadoes in Ontario that induced damage to infrastructure. The damage to the buildings surveyed is characterized based on different levels and discussion is included regarding the way residential buildings should be built to assure resilience if they are affected by tornadoes. The field investigation based on the performance of the examined buildings suggests a need for new design and retrofit methods to strengthen buildings envelopes. The buildings should have adequate anchorage of the walls into the foundation and well-constructed connections of the roof to the walls.