Türkiye's Seismic Context
Türkiye is one of the world's most seismically active countries. The North Anatolian Fault — running across northern Anatolia from eastern Turkey to the Marmara Sea and beyond — has produced some of the most destructive earthquakes of the 20th and 21st centuries, including the 1999 İzmit (Mw 7.6) and Düzce earthquakes, and more recently the 2023 Kahramanmaraş earthquakes (Mw 7.8). The Mediterranean and Aegean coastal regions, including Antalya, experience seismic activity from both the North Anatolian system and the Hellenic subduction zone to the west.
Our Türkiye Project
Project P-2023-091 in Antalya involved entertainment steel support structures in a region classified as high seismic hazard. The design applied Turkish AFAD (Disaster and Emergency Management Authority) seismic hazard maps to determine site-specific spectral accelerations, combined with AISC 341 seismic detailing provisions to ensure ductile behaviour under the Level 2 seismic event. Connection design was governed by capacity design requirements — connections designed stronger than the yielding elements to ensure inelastic deformation occurred in the intended locations. The project required explicit documentation of both the Turkish seismic hazard data and the AISC seismic design methodology for the client's review team.
AFAD Seismic Hazard Data
Turkey's Disaster and Emergency Management Authority (AFAD) publishes the official seismic hazard maps for the country, based on probabilistic seismic hazard analysis updated following the 2023 earthquakes. For Antalya, the AFAD maps show Peak Ground Acceleration (PGA) values and spectral acceleration ordinates at 2% probability of exceedance in 50 years — consistent with the ASCE-7 design return period. These values were used to determine the Design Spectral Acceleration parameters SDS and SD1 following ASCE-7 methodology adapted to the Turkish hazard data.
Soft Soil Amplification
Antalya's coastal deposits include soft alluvial and marine sediments that significantly amplify seismic ground motions relative to rock reference conditions. Site Class D soil conditions at the Antalya project site applied site amplification factors Fa = 1.6 and Fv = 2.4 to the reference spectral accelerations — increasing the design spectral accelerations substantially above the rock-site values shown on the AFAD maps. This amplification is frequently underestimated in simplified assessments and must be explicitly quantified in any rigorous seismic design for soft soil sites.
Engaging Us for Türkiye Projects
We provide structural design services for Türkiye projects with AFAD seismic hazard determination, AISC seismic design methodology, and documentation formatted for the client's review requirements. Contact us with your project location, structure type, and applicable code requirements.