ODIT Construction Company,
ATMAS Group
is the Official Distributor in Türkiye
Blast engineering / pre-assessment
Has the rebound load been calculated for your project?
After the blast wave passes, the structure experiences a reverse load. This rebound effect directly affects the blast door lock system, connection details, and wall reinforcement.
In many projects, this critical calculation is skipped during the design phase; the problem often surfaces during acceptance testing or field application. Has it been checked in your project?
Blast load calculation Door & lock detail CBRN and sealing
3-Step Technical Pre-Check
Are the critical calculations complete for your project?
Pressure class, rebound load, and conversion feasibility must be assessed together. The brief check below shows which points need to be verified.
1
2
3
Step 1 / 3
What threat scenario is your project designed for?
Check result: Even in a low-risk scenario, separate resistance levels for the entrance, emergency exit, roof, and exterior wall must be verified. Does your equipment specification match these values?
Check result: In a high-risk scenario, structural elements and equipment classes must be assessed against higher kPa values. Door, filtration, and sealing selection should be made according to this class.
Check result: In command center projects, not only structural resistance but also continuity, ventilation, pressurization, and equipment compatibility must be checked within the same protection class.
Check result: In critical facility and forward command scenarios, load level, equipment class, and acceptance test requirements must be addressed together. Incomplete specification can create serious risks during implementation.
Step 2 / 3
Is the rebound load explicitly calculated in the project documents?
Check result: This is a good start. However, it should also be verified whether the rebound calculation is consistent with the blast door lock system, anchors, and wall reinforcement.
Check result: An uncertain rebound calculation can create risks during acceptance testing and implementation. This load particularly affects door lock, hinge, anchor, and reinforcement details.
Check result: If the rebound calculation is absent from the document, the structure may have been assessed only for positive pressure. This can lead to critical deficiencies in door, connection, and reinforcement details.
Step 3 / 3
What stage is the project at?
Check result: In existing structure conversion, the structural system, ventilation, sealing, escape routes, and equipment placement must all be checked together.
Check result: If the correct protection class is determined early in a new structure, reinforced concrete details, equipment spaces, and CBRN systems can be planned more effectively.
Check result: The feasibility stage is the best time to identify technical risks before incorrect equipment or an insufficient resistance class is selected.
Genel teknik yorum
The pressure class, rebound load, and equipment compatibility in your project must be checked together. Without clarifying these three areas, the correct door, filtration, pressurization, and sealing cannot be selected.
Global urgency
The world is rebuilding its shelter infrastructure. Is your project ready for this transformation?
Finland is developing standards, Germany is re-inventorying metro stations and basements, Poland is enacting a new civil protection law, and Japan and South Korea are strengthening their digital shelter infrastructure under active threat.
Looking at global developments, you may have limited time to complete your project.
Technical requirements not planned today may mean higher compliance costs and more difficult revisions tomorrow.
65.000
Sweden's Cold War-era shelters are on the renovation agenda.
€40+ billion
Germany's shelter infrastructure requirement under discussion for the initial years and beyond.
%114
Switzerland's shelter capacity relative to population is unique on a global scale.
Reference Models
Finland
One of Europe's most comprehensive shelter legal frameworks. A reference model with a periodic maintenance approach and standard development work.
Switzerland
A unique system with shelter capacity exceeding the population, mandatory space per person, and cost sharing.
Israel
Mandatory Mamad safe room requirement since 1992 and alarm/shelter practice operating under real attack conditions.
Singapore
Mandatory household shelter in every apartment since 1998; city-wide coverage target.
Norway
Rock shelter tradition, NATO civil planning processes, and an active role in Baltic region coordination.
Countries in Rapid Transformation
Sweden
Rapid transformation with a large-scale shelter renovation budget and Total Defence doctrine for 2025–2030.
Germany
Existing 579 shelters protect less than one percent of the population; metro stations, parking facilities, and public basements are being re-inventoried.
Poland
The civil protection law entering into force in 2025 addresses a strong military and resilient society approach together.
Lithuania
Capacity increase between 2022–2024 and an active implementing role in the Ukraine school shelter program.
Estonia
Stands out in NATO's Eastern Flank with a digital shelter matching platform and dual-use shelter approach.
Latvia
Increasing capacity in Baltic coordination with public building and basement retrofit programs.
Active Combat and Threat Experience
Ukraine
National shelter network strategy extending to 2034 and unique technical lessons from wartime conditions.
Japan
An application showing shelter locations against missile threats and the decision to move command centers underground.
South Korea
Mandatory civil defense drills, metro shelter network, and threat infrastructure operating with the Emergency Ready App.
Taivan
A critical case with the All-of-Nation Defence Resilience Committee and civil defense law discussions.
Iran
A reference influencing civil shelter design with hardened underground construction engineering and deeply buried facilities.
Russia
Soviet-era shelter renovation programs, mobile protected shelter production, and metro-based defense heritage.
Countries That Have Launched Active Programs
Netherlands
NATO civil planning, EU directives, and critical infrastructure dual-use assessment.
Denmark
Seeking a new model through coordination reform with the Ministry of Resilience and Preparedness.
Czech Republic
Bringing the historical shelter inventory onto the modernization agenda and joining the Ukraine Coalition.
Avusturia
A country to follow with its participation in the Ukraine Coalition and neutrality doctrine discussions.
Belgium
Important in terms of critical infrastructure modeling due to its role as an EU hub and its field implementation role through Enabel.
Ireland
Contribution to the Ukraine school shelter program; a high-impact approach with a small budget.
Countries to Watch for Different Reasons
China
The Renmin Fangkong system, shelter requirements in urban planning legislation, and dual-use underground spaces.
Saudi Arabia
Despite a high defense budget, a lack of current civil shelter legislation; a regional gap and opportunity area.
BAE
Public shelter policy is limited; however, private sector and luxury shelter demand is growing.
Qatar
The underground command and base infrastructure at Al-Udeid base is a critical example for military underground engineering.
Kazakhstan
Should be followed due to Soviet infrastructure heritage, defense industry facilities, and military relations with Turkey.
Azerbaijan
A country that experienced the need for shelters in real urban warfare conditions through the Karabakh experience.
When this transformation begins, the compliance cost of existing structures can increase rapidly.
In projects planned today, technical requirements can be integrated during the construction phase. Retrofitting later may be more costly in terms of equipment, detail, and acceptance testing.
- Blast loads
- Rebound effect
- CBRN infrastructure
- Equipment compatibility
The most frequently missed calculation
A shelter must be prepared not only for pressure, but also for the reversal of load direction.
“How many kPa can it withstand?” is an important question; but it is not sufficient on its own. The rebound that occurs when the blast effect ends can have critical consequences, especially on door locks, anchors, connection plates, and reinforced concrete reinforcement details.
- 1Blast door lock systemRebound load can create unexpected stresses in lock and hinge details.
- 2Wall reinforcement and anchoringDetails designed only for positive pressure may be insufficient under reverse load.
- 3Acceptance test riskMissing calculations often become visible not during the drawing stage, but during testing and implementation.
Correct assessment
The resistance of a project is not determined by a single number.
Threat scenario, structural geometry, intended use, soil conditions, and equipment class must be assessed together.
01
Threat scenario
Explosion pressure, distance, impulse duration, and direction of impact form the initial design parameters.
02
Structural behavior
Static equivalent load, SDOF dynamic analysis, or advanced FEM approach is selected based on need.
03
Equipment compatibility
Door, filter, valve, sealing, and ventilation elements are specified according to the same protection class.
Pressure class
How many kPa should it withstand?
Different usage scenarios require different pressure resistance, reinforced concrete details, and equipment class.
| Structural Element | Civilians (low) | Civilians (high) | Command Center | Forward Command |
|---|---|---|---|---|
| Roof | 100 kPa | 300 kPa | 600 kPa | 1.800 kPa |
| Exposed exterior wall | 200 kPa | 600 kPa | 1.200 kPa | 3.600 kPa |
| Entry section | 50 kPa | 150 kPa | 300 kPa | 600 kPa |
| Emergency exit | 100 kPa | 300 kPa | 600 kPa | 1.800 kPa |
These values must be verified through engineering assessment according to project scope, threat level, and relevant standards. Each value affects a different equipment class, reinforced concrete detail, and ventilation design.
Blast effect
The blast wave does not arrive at the structure as a single load.
Correct shelter design evaluates the blast effect together with multiple physical impacts.
01
Airblast wave
Pressure rises suddenly, decreases over time, and a negative phase forms.
02
Ground shock
In buried structures, soil type and depth directly affect the outcome.
03
Fragment effect
Fragments generated after the explosion affect wall and door details.
04
Rebound
The structure receives load in the reverse direction; this is critical for the door, connections, and structural system.
CBRN protection
Protection is not only against explosions.
Modern shelters must also be addressed comprehensively against chemical, biological, radiological, and nuclear threats. Filtration, pressurization, sealing, and continuity are all parts of the same engineering framework.
- ✓CBRN filtrationIncoming air is conditioned through a multi-layer filtration system.
- ✓Positive pressureThe interior is maintained at a controlled pressure relative to the exterior.
- ✓SealingDoor and structural joints are assessed according to the gas-tightness principle.
Implementation partner
Atmas technology is applied to the project together with ODIT engineering.
We do not only supply products. We jointly manage threat analysis, load calculations, equipment selection, field implementation, and commissioning.
Threat analysis and shelter class determination
Blast load calculations and rebound check
Equipment specification and Atmas product selection
Technical supervision during implementation
CBRN filtration and pressurization setup
Acceptance testing and commissioning support
Could a critical calculation have been missed in your project?
Share your project type and current stage; let us provide a pre-assessment of the correct analysis level, equipment needs, and feasibility.
Technical check
Let us check whether there is a risk in your project.
Share your project type and stage; let us provide a pre-assessment of rebound load, pressure class, equipment selection, and feasibility.