How to Build an Earthquake-Resistant House?

Earthquake-Resistant Structure: Basic Concepts

A large part of Turkey is located on active seismic belts, and the 2023 Kahramanmaraş earthquakes once again showed the direct impact of construction quality on human life. So how is a truly earthquake-resistant house built from a scientific and engineering perspective?

An earthquake-resistant structure is not one that doesn't "feel" the earthquake; it is one that dissipates earthquake energy in a controlled manner, remaining standing without collapsing even if it sustains damage. This distinction is critical.

1. Soil Survey: The Beginning of Everything

Even the best-designed structure can face disaster if placed on the wrong ground. A soil survey covers:

Drilling and laboratory tests: Soil class (ZA–ZE) is determined.
Liquefaction risk analysis: Critical especially in riverbeds and fill areas.
Local soil amplification: Soft soils can amplify seismic waves.
Foundation system recommendation: The soil survey determines the appropriate foundation type (raft, pile, etc.).

TBDY-2018 clearly states the requirement for soil surveys for all new structures.

2. Structural System Selection

Three main systems are suitable for earthquake-resistant design:

Reinforced Concrete Frame System

This system, where the column-beam frame is supported by shear walls, offers high seismic performance with correct reinforcement and concrete quality. The most critical point is lateral ductility in flat slab floors.

Steel Frame System

Its energy dissipation capacity is high thanks to its ductility. Connection design (moment-resisting or concentric diagonal) directly determines seismic performance.

Light Steel Frame (LSF)

Load distribution is homogeneous thanks to the load sharing of numerous small elements. Lateral rigidity is provided with OSB or cement board cladding.

3. Avoiding Irregularities

TBDY-2018 limits in-plan and in-height irregularities. In the design of an earthquake-resistant house:

Soft story: Floors that are not much more rigid than the lower floor are the first elements to collapse in an earthquake. Piloti (open ground floor) application without sufficient shear walls/walls is dangerous.
Torsional irregularity: Asymmetric distribution of mass and rigidity makes the structure susceptible to torsion, and thus additional damage.
Adjacent building collision (Pounding): Insufficient expansion joint space between buildings causes seismic impact.

4. Column and Beam Design

The golden rule of earthquake-resistant reinforced concrete design: the "Strong column – weak beam" principle. Damage should occur in beams and in a controlled manner; columns must maintain their integrity.

Column dimensions: While a minimum of 30×30 cm is recommended, it needs to be enlarged in multi-story structures according to soil class and seismic zone.
Column-beam junction zones (node points) must be strengthened with dense stirrups.
Confinement reinforcement (stirrup) spacing must meet the limits specified in TBDY-2018.

5. Shear Walls

Shear walls, which carry horizontal seismic loads, are one of the most effective elements of seismic safety in buildings. The ratio of shear wall area to floor area (shear wall density) is bound to minimum limits in TBDY-2018. Well-positioned shear walls both prevent torsion and increase lateral rigidity.

6. Concrete Quality and Reinforcement

Concrete class: A minimum of C25 (characteristic compressive strength 25 MPa) is recommended in seismic zones.
Reinforcement: High ductility steel of class B420C or B500C must be used.
Concrete cover: Protection of reinforcement against corrosion is critical for long-term integrity; a minimum cover of 2.5–3 cm must be applied.
Vibration: Insufficient vibration causes voids (honeycombing) in the concrete and loss of strength.

7. Foundation System

The foundation system, determined according to the soil survey, is the most critical interface between the structure and the ground. In weak soils:

Raft foundation distributes the load over the widest area.
Pile foundation transfers the load to solid bedrock or a bearing layer.
Ground improvement methods (jet grouting, soil nailing, etc.) can be applied.

8. Building Inspection

Building inspection, which is a legal requirement in Turkey, is the guarantee of putting seismic safety into practice. No structure can claim to be earthquake-resistant without concrete sampling, reinforcement inspection, and formwork and concrete pouring inspection.

Checklist: 10 Steps for an Earthquake-Resistant House

✅ Have a soil survey conducted.
✅ Have a structural project prepared in compliance with TBDY-2018.
✅ Work with a licensed building inspection firm.
✅ Write minimum C25 concrete quality into the contract.
✅ Use B420C/B500C ductile reinforcement.
✅ Have the adequacy of shear walls approved by an engineer.
✅ Never reduce column dimensions.
✅ Leave a sufficient expansion joint with the neighboring building.
✅ Take samples and have them tested at every concrete pour.
✅ If using a piloti floor, ensure sufficient shear walls are provided.

Conclusion

Building an earthquake-resistant house does not require a large cost; safe structures can be built with a standard budget with correct engineering decisions and meticulous application. As Tunahanyeniçeri, we commit to delivering safe structures in every project with our seismic design approach based on TBDY-2018.