This service answers
“Will this building stand up in a strong earthquake?”
You receive: Seismic evaluation, retrofit scheme with performance objective, drawings and supervised works
Why seismic retrofitting matters in Bangladesh
Bangladesh sits close to the boundaries of the Indian, Eurasian and Burma plates, and BNBC 2020 divides the country into four seismic zones, from Zone 1 in the south-west to Zone 4 in the north-east around Sylhet. Dhaka lies in Zone 2. Much of the existing building stock was designed before current seismic provisions, or without effective engineering supervision, and soft deltaic soils can amplify shaking.
Common weaknesses we find
- Soft storeys — open ground floors used for parking or shops, with walls above
- Weak columns and strong beams, so damage would form in the columns
- Too few, too widely spaced column ties, giving little ductility
- Irregular plans and abrupt changes in stiffness
- Added floors that increase mass without increasing strength
Our approach
- Evaluate. Starting from a Detailed Engineering Assessment, we analyse the building for BNBC 2020 seismic demands, using ASCE 41 evaluation methods where a performance-based approach is appropriate.
- Set the objective. With you, we agree the target: life safety for most buildings, higher performance for hospitals, schools and critical facilities.
- Design the scheme. Global measures add lateral strength and stiffness; local measures add ductility to individual members.
- Build and verify. Supervised works with quality control at every stage.
Techniques
| Measure | What it does |
|---|---|
| New RC shear walls | Adds stiffness and strength; very effective for soft storeys |
| Steel bracing frames | Adds lateral capacity with little weight; fast to install |
| Column jacketing (RC, steel) | Increases column strength and confinement |
| CFRP wrapping | Increases ductility and shear capacity with negligible added size |
| Foundation upgrades | Lets the foundations carry the forces the new elements attract |
Questions owners ask
Which seismic zone is my building in?
BNBC 2020 has four zones. Dhaka is in Zone 2; the north-east, including Sylhet, is in Zone 4, the highest. We confirm the zone and soil class for your exact site as part of the evaluation.
Can a building be made completely earthquake-proof?
No building is earthquake-proof. Seismic retrofitting aims for a defined performance — usually that the building does not collapse and people can get out safely — and higher targets for critical facilities.
Are lightweight steel buildings safer in earthquakes?
Seismic force depends on mass, so lighter buildings attract smaller forces. They still need correctly designed connections, bracing and anchor bolts.