Analysis of the damage potential of the Kocaeli (Turkey) earthquake of 17 August 1999

The damage inflicted by the Kocaeli earthquake on structures in general, and relatively modern RC buildings in particular, is perhaps the worst seen in many years, and certainly the worst in Europe in recent history. Early reports attributed the damage to construction quality and lack of seismic detailing. The purpose of this short paper is not to dispute this claim, but rather to widen the discussion and shed light on other possible contributing factors. It is indicated, by well-verified inelastic dynamic analysis, that the demand imposed by some of the records measured in the severely affected area is exceptionally high. A full-scale model structure recently tested at the Joint Research Centre, Italy, is used for comparison purposes. It has withstood experimentally demand imposed by an artificial record generated to represent a European earthquake with a 975 years return period (well over the code-specified limits of 475 years) with limited damage. Analysis has also indicated that the frame would have easily survived the Arleta fire station record from Northridge in 1994. The structure would have certainly collapsed if subjected to the records of Yarimca from the epicentral area, or Duzce close to the fault rupture, both of the Kocaeli earthquake. The deformation demand imposed on RC structures similar to that considered in this paper is much higher than that implied by modern European codes.