DAMAGE TO CONCRETE STRUCTURES DUE TO THE 1994 NORTHRIDGE EARTHQUAKE

Observations on damage to concrete structures, due to the 1994 Northri dge earthquake, are reported from a Canadian code perspective. Most of the damaged structures were older, nonductile, structures that do not conform to current design and detailing requirements. Concern is expr essed about the seismic hazard of older Canadian structures having sim ilar deficiencies. A significant number of parking structures suffered extensive damage and a number of precast concrete parking structures collapsed. Deficiencies in these structures include lack of proper dia phragm connections, a mix of gravity load columns with ductile framing , inappropriate number and distribution of shear wails, torsional effe cts caused by ramps, and the creation of short columns due to geometri c features. This earthquake also demonstrated the deficiencies in conn ections of pre-1973 tilt-up structures.