The first seismic code in Turkey was developed following the 1939 M 7.9 Erzincan earthquake. In each period, the design philosophies and requirements were as modern as other seismic codes. Reduction factors for system ductility were indirectly introduced in the 1975 code. Shear walls are not commonly used. Concrete components are generally cast in place with site batching common for residential construction.
Precast concrete is used only for beams, columns, and walls in industrial buildings.
Steel moment-resisting frames and braced frames are used for industrial construction but almost never for residential construction. Damage was localized in the larger cities with the greatest concentrations of collapsed buildings located at sites where the foundation materials failed due to liquefaction. Only a few residential structures were constructed using reinforced concrete shear walls, and these buildings performed well. Most of the structural failures in the reinforced concrete frame buildings observed by the reconnaissance team could be traced to a lack of transverse reinforcement in columns and beam-column joints, to inadequately anchored longitudinal reinforcement, to poorly located lap splices of longitudinal reinforcement, and to plan and vertical irregularities. Poor quality concrete was observed in a number of the failed buildings.