Performance of reinforced concrete buildings during the August 17, 1999 Kocaeli, Turkey earthquake, and seismic design and construction practise in Turkey

A large number of reinforced concrete buildings collapsed or were heavily damaged during the 7.4 magnitude earthquake that struck northwestern Turkey on August 17, 1999. Recorded peak ground accelerations were relatively low (0.3 g–0.4 g) compared to the magnitude of the structural damage, and the elastic acceleration response spectra from the recorded motions were comparable with the elastic design spectra specified in the current Turkish seismic code. Seismic code requirements are discussed and compared with observed details. Many structural deficiencies were highlighted by the earthquake damage, including: reinforced concrete columns with insufficient confinement and transverse reinforcement, 90-degree hooks at the end of column ties, poor detailing in beam-column joint regions, strong-beam and weak-columns, soft and weak stories, and poor quality construction. Buildings with shear wall structural elements generally performed well.