Performance of Precast and Prestressed Concrete in Mexico Earthquake

The extreme severity of the earthquake and major aftershock that hit the west coast of Mexico, September 19 and 20, 1985, caused the collapse of several hundred multistory buildings in Mexico City [about 400 km (250 miles) away from the epicenter]. An estimated 10,000 people lost their lives and countless more were injured. In addition, a quarter million people lost their homes. Most of the collapses were reinforced concrete framed buildings in the range of six to fifteen stories. Five of the collapsed buildings contained precast concrete components as part of their structural systems. Many buildings and parking garages in Mexico City utilizing precast concrete elements withstood the earthquake without distress. In Lazaro Cardenas [about 30 km (19 miles) from the epicenter], large fully precast buildings in the fertilizer plant resisted the earthquake exceptionally well. Also, throughout the country and within the cities, the concrete bridges withstood the earthquake without damage. This report presents the author's observations of the performance of precast and prestressed concrete during his visits to Mexico City and Ldzaro Cardenas. However, prior to getting into this discussion, it is necessary to describe the unique seismological aspects of the earthquake and the resulting overall damage.