Damage to buildings due to the 1989 Loma Prieta earthquake — a Canadian code perspective

Abstract

Damage to building structures during the October 17, 1989, Loma Prieta earthquake prompted site visits by the authors. This paper presents examples of damage to buildings constructed with reinforced concrete, steel, masonry, and timber. The observed damage is used to illustrate some of the seismic design clauses in the 1990 National Building Code of Canada, the 1984 Canadian Standards Association (CSA) Standard for the Design of Concrete Structures for Buildings, and the 1989 CSA Standard for the Limit States Design of Steel Structures. The important roles played by the presence of soft soil, poor structural layouts, inadequate detailing, the lack of reinforcement in masonry, as well as inadequate connections to foundations are highlighted. Examples of the performance of upgraded structures are also given, and the concern over the presence of existing hazardous buildings in significant seismic zones in Canada is emphasized. Key words: seismic design, earthquake, Loma Prieta, structures, codes, concrete, steel, masonry, timber, upgrading.