Turkey's Earthquake Code and School Buildings: What Does TBDY 2018 Require?
- The Turkish Building Earthquake Code (TBDY 2018) was published in the Official Gazette on 18 March 2018 and took effect on 1 January 2019.
- Schools are classed among buildings where people stay for long periods in large numbers and are designed with the highest importance factor, I = 1.5.
- The importance factor increases design seismic forces, requiring a stronger structural system than a home of the same size on the same soil.
- Geotechnical surveys, independent building inspection and on-site quality control keep the code from remaining on paper.
A school building holds hundreds — sometimes thousands — of children at once. That is why Turkey's earthquake code treats schools not as ordinary buildings but as structures in the highest importance class. Drawing on the school campuses ÇET Yapı has built in Istanbul, Ankara, İzmir, Kayseri and Hatay, here is what TBDY 2018 means for school buildings.
TBDY 2018 in brief
The Turkish Building Earthquake Code (TBDY 2018) was published in the Official Gazette on 18 March 2018 and came into force on 1 January 2019. Since then, seismic hazard is no longer defined by old province-based zones but by the AFAD Turkey Earthquake Hazard Map, specific to each parcel's coordinates.
Why schools have an importance factor of 1.5
The code groups buildings into building use classes and assigns each a building importance factor (I):
| Building use class | Examples | Importance factor |
|---|---|---|
| BKS 1 | Buildings needed immediately after an earthquake (hospitals, fire stations, etc.) and buildings where people stay for long periods in large numbers, such as schools and dormitories | 1.5 |
| BKS 2 | Buildings where people gather in large numbers for short periods (shopping centres, sports facilities, etc.) | 1.2 |
| BKS 3 | Other buildings (housing, offices, hotels, etc.) | 1.0 |
The importance factor directly scales the design seismic forces: a school on the same soil as a home of the same size is designed for roughly 50% higher forces.
Five steps to seismic safety in school projects
- Parcel-specific hazard analysis: obtain the parcel's hazard parameters from the AFAD map.
- Geotechnical survey: boreholes and lab tests define the soil class and any liquefaction risk; weak soils may require ground improvement or special foundations.
- Structural design: wide classroom and sports hall spans and tall volumes such as conference halls must be solved without creating irregularities.
- Independent building inspection: the inspection firm is responsible for checking that construction follows the design, including concrete and reinforcement.
- Workmanship: the code only matters if it is applied correctly on site; formwork, reinforcement and concrete pours should be documented.
Existing school buildings
Schools built under pre-2019 codes should undergo a performance assessment by a qualified engineering team. Depending on the result, the building may be strengthened, renovated or rebuilt. ÇET Yapı's renovation projects such as Beşiktaş Geo College and the Cevizlibağ and Güzelce Doğa Colleges are examples of adapting existing educational buildings to new needs.
Checklist for school investors
- Find out the parcel's seismic hazard parameters before design starts.
- Treat the geotechnical survey as the foundation of the design, not a cost item.
- Check that the structural design uses an importance factor of 1.5.
- Archive inspection reports and concrete test results.
- Define quality-control and testing responsibilities clearly in the contract.
This article is for general information; design and assessment must be carried out by qualified engineers.
Frequently Asked Questions
What importance factor applies to school buildings in Turkey?
Under TBDY 2018, schools are among buildings where people stay for long periods in large numbers, with a building importance factor of I = 1.5 — the highest in the code.
When did TBDY 2018 come into force?
It was published in the Official Gazette on 18 March 2018 and came into force on 1 January 2019.
How does an importance factor of 1.5 affect cost?
Higher design forces may require more concrete and reinforcement in the structure. But the structural system is only part of the total budget; for critical buildings such as schools, the difference is a necessary safety investment.
How is the seismic safety of an existing school checked?
A qualified engineering team carries out a performance assessment of the existing structure using material samples, reinforcement detection and soil data to determine whether it meets the code's targets. Strengthening or reconstruction is decided accordingly.
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