1753 1 Earthquake Eng. Res. Center, Dept. of Civil Eng.,Middle East Tech. University, 06531, Ankara, Turkey, a06074@metu.edu.tr 2 Earthquake Eng. Res. Center, Dept. of Civil Eng.,Middle East Tech. University, 06531, Ankara, Turkey, turelg@metu.edu.tr 3 Earthquake Eng. Res. Center, Dept. of Civil Eng.,Middle East Tech. University, 06531, Ankara, Turkey, a03516@metu.edu.tr THE ADANA-CEYHAN EARTHQUAKE OF 27 JUNE 1998: SEISMIC RETROFIT OF 120 R/C BUILDINGS Haluk SUCUOĞLU 1 , Türel GÜR 2 And Polat GÜLKAN 3 SUMMARY A severe earthquake measuring M s 6.2 occurred near the city of Ceyhan (population 100 000) in Southern Turkey on 27 June 1998. Although the focal distance to Ceyhan was 32 km, fault rupture was directed towards Ceyhan, causing heavy damage in the city as a result of a strong motion with a PGA of 0.28 g. Out of a total number of 146 casualties, 86 were in Ceyhan. Twelve R/C buildings collapsed and 120 were classified as moderately damaged in Ceyhan. These 120 multistory buildings have been inspected and their seismic retrofit projects have been prepared by the Earthquake Engineering Research Center of the Middle East Technical University (METU/EERC). The retrofit works include detailed damage assessment and structural evaluation of the existing buildings, selection of the retrofit scheme, and final performance verification by the capacity spectrum method. Cast in place concrete infill walls are employed as the primary elements of seismic retrofit. The selected retrofit scheme has provided the required seismic safety and economy. INTRODUCTION Three severe urban earthquakes occurred in Turkey recently, in 1992, 1995 and 1998, in three different seismo- tectonic environments indicated in Figure 1. These earthquakes caused substantial damage to buildings in the cities of Erzincan, Dinar and Ceyhan. According to the Disaster Law in Turkey, each residential or commercial building affected by a natural disaster in a disaster area is quickly assessed by an official damage assessment team, and awarded a damage grade, light, moderate or severe. These inspection teams rate damage by applying uniform, simple procedures developed seperately for reinforced concrete and masonry buildings [Gülkan et al. 1994]. The severely damaged buildings are demolished and the moderately damaged buildings are entitled for seismic retrofit with financial loans provided by the government. In the aftermath of these three earthquakes, requests have been made by the Ministry of Public Works and Settlement on the expertise available at the METU/EERC for involvement in the rehabilitation works. The scope of this involvement prior to Ceyhan was developing seismic retrofit strategies for 29 three to four story R/C school buildings in Erzincan, and 34 three to six story R/C residential apartment buildings in Dinar [Wasti and Sucuoğlu, 1999]. After the 1998 Adana-Ceyhan earthquake [Gülkan, 1998], seismit retrofit works of all 120 moderately damaged R/C residential apartment buildings in Ceyhan have been assigned to METU/EERC. This building stock is composed of 3-9 story buildings, with a total floor area of 220 000 sq m. METU/EERC has coordinated geotechnical and structural engineering consultants in undertaking this task. The retrofit design of all buildings has been completed in June 1999. Technical supervision of construction will also be done by the same organization. This paper reviews seismic and engineering aspects of the Adana-Ceyhan earthquake and summarizes the seismic retrofit works carried out by METU/EERC.