The earthquake that struck northern Turkey on August 17, 1999 caused widespread damage, even to buildings far from its epicenter. Among the structures affected was the new passenger terminal at Ataturk International Airport in Istanbul, then under construction. The local build-operate-transfer consortium, Tepe-Akfen-Vie, and its construction consultant, Turner International LLC, retained Thornton Tomasetti and Tuncel Engineering of Istanbul to analyze the damage, evaluate the seismic resistance of the structure and develop a scheme to improve its seismic performance. The team devised an ingenious plan, including solutions never before used, for a seismic upgrade that would enable the terminal to remain functional in the event of another major quake. The process, from evaluation through design and implementation, was accomplished in less than four months, allowing the terminal to be completed in time for its originally scheduled inauguration in January 2000.
The reinforced concrete superstructure and steel space-frame roof of the 240-meter (787.4-foot) by 168-meter (551.18-foot) three-story terminal were nearly 95 percent complete when the earthquake struck. The damage to the building was attributed to the incomplete state of certain key structural elements. The need for remediation became an opportunity to enhance and improve the building’s seismic performance, in effect, to perform a seismic retrofit on a structure still under construction.
The retrofit scheme was developed through an unusual combination of techniques. The engineers brought in specialists in seismic analysis who used sophisticated research tools to help identify the damage, determine how to reinforce the building and test the efficacy of the proposed solutions. The technical team decided to isolate the steel-frame roof, by installing friction pendulum bearings as seismic isolators at the tops of the columns supporting it. These allow the roof to swing independently from side to side during an earthquake, reducing the demand on the columns below. The concrete columns were steel-jacketed and filled with grout for increased resistance and ductility.
The rapid retrofit allowed the terminal to open on time and enabled the owner to begin realizing revenues quickly. The scheme, which avoided interference with completed portions of the building, saved both time and expense. In strengthening seismic resistance beyond local design requirements, the upgrade should enable the building to withstand a design magnitude quake 50 percent stronger than that of 1999 and continue to perform its vital role in permitting access in and out of the cosmopolitan city after a serious seismic event.
This project was awarded a Grand Award from the American Council of Engineering Companies for the 2002 Engineering Excellence Awards as well as a Diamond Award from the New York Chapter of the American Council of Engineering Companies, also in 2002.