Not all blast-resistant modular buildings are created equally
When considering the strength of blast-resistant modular buildings, it may seem fine to group them all into the same category. However, there are differences in their engineering, design and construction that must be pointed out. In this article, we explain the differences between the various steel blast-resistant buildings, showing you why RedGuard Specialist Services’ blast resistant modular buildings are the kind of safe place you would want to be in if you found yourself in a blast event.
Are all blast-resistant modular buildings safe?
As the name suggests, all blast-resistant buildings will offer some level of protection against a blast. They also have appropriate applications depending on their blast rating and where they are placed on site. However, some designs provide a higher level of protection compared to others. This kind of blast resistant building is more appropriate for use near processing units in hazardous areas. Other buildings are not as strong and should therefore be placed in areas of lower hazards.
What types of blast-resistant structures are available?
There are a few different choices when it comes to blast-resistant structures. Here are some types of blast resistant buildings for you to consider.
Brick and mortar structures
Conventionally designed (brick and mortar) structures can be placed in hazardous areas. These buildings can be designed and built to your exact blast specifications and you can have them outfitted with all the amenities you need. However, these types of buildings take time to construct. On top of that, having them made blast-resistant, takes more time and money compared to modular building options.
A newer type of blast-resistant structure are precast concrete buildings. They take less time to build than a traditional brick and mortar structure, but the price of these buildings can be much higher than steel blast-resistant modular buildings, or even brick and mortar buildings.
Another type of temporary blast-resistant structure is the blast-resistant tent, which is a fabric-based structure, reinforced with loose steel support beams, or with air columns. These are usually used for large mess halls or gathering places.
Although the blast-resistant tent will provide some temporary protection, the fabric in this kind of structure design has not been practically proven in relation to projectiles, which during a blast have been seen to reach areas outside of the blast zone. Blast-resistant tents have large deflections during a blast event, which means that internal items must be several feet away from the walls. Furthermore, due to their structure and arrangement, the actual safe space available for use is much smaller than the footprint of the tent itself.
Steel blast-resistant modular buildings
Steel blast-resistant modular buildings are the most common structure in this group and for good reasons. They are readily available for permanent or temporary utilisations. As such, they can be rented and added during turnarounds to house temporary workers, and can be removed when no longer necessary. They can be also installed and anchored as permanent structures. Steel blast-resistant modular buildings are often completely customised for large capital projects.
Within this category, there are differentiations among companies regarding the engineering and design. As such, it is essential to ask the companies you are considering to explain what the most important parts of their design are and how they protect in case of a blast. Here we will explain the similarities and differences among various steel blast-resistant modular buildings.
How are steel blast-resistant modular buildings similar?
1. All steel blast-resistant modular buildings are blast-rated
As mentioned earlier, all blast-resistant modules are blast rated to some degree. Therefore, while some of them still look like containers, it is important to point out that quite a bit of engineering went into the underlying designs that make these modular buildings safe.
2. Steel blast-resistant modular buildings often look similar
People often compare blast-resistant modular buildings to containers, or Conex boxes. However, they are NOT containers.
Although many of them look like metal shipping boxes, it is important to note that steel blast-resistant modular buildings can also be outfitted with aesthetic design elements to look like brick-and-mortar buildings and match other facilities nearby.
Their mobile nature is one of the reasons they all look the same. To save on transportation costs, blast-resistant modular buildings are made to be carried and transported with the use of the same forklifts, semi-trucks, cranes, and even trains that carry Conex or ISO-boxes. Therefore, even though steel blast-resistant modular buildings are not shipping containers, they use some ISO specifications (like corner blocks) ensuring the ability to transport and move them as needed.
3. Steel blast-resistant modular buildings flex during a blast
When a blast wave impacts the surface of a steel blast-resistant modular building, its steel walls “flex”. This means that the walls move a minimal amount to absorb the energy of the blast wave and protect the building’s occupants and equipment.
Other building types, particularly precast concrete, are rigid and don’t flex like steel. Instead, they rely solely on the strength of the building material. The rigidity of this kind of design does not absorb or dissipate the blast wave, and will drive all the energy from the blast to the building’s connection points.
What are the differences among various steel blast-resistant modular buildings?
1. Steel walls and ceiling
All steel blast-resistant modular buildings utilise steel walls and ceilings, but there are differences in the types. There are two main options: thick, flat steel sheeting or an S-curve, or corrugation. Corrugation in a steel building design adds strength to the structure. However, it should never be the only protection of the building.
You can think of the corrugated steel as similar to that of a cardboard box. In between the sides of a standard cardboard box, you will find another piece of paperboard that is bent into an S-curve design. This makes the walls of the cardboard box stronger, more stable, and prevents it from bending into itself. A similar notion led to the use of corrugated steel in blast-resistant buildings design.
2. Blast-resistant frame structure
Companies build their structures with steel frames of heavy beams, relying on them to take most of the blast load, but they position them differently. In some designs, the internal beams may be several feet apart, even ten feet apart. In these designs, if one of the beams fails, the next beam could be several feet away. This allows for large deformation in the corrugated panels and makes them more susceptible to higher response (damage) levels or collapse.
More robust designs utilise more closely spaced beams to provide a higher protection level. This close spacing of steel beams is also referred to as redundancy. Buildings with redundancy in their frame design have beams spaced closely to carry the majority of the blast in the event of an explosion. In this design, if one of the beams fails, there is another beam nearby to help pick up the blast load.
What is the perfect combination?
When it comes to blast-resistant building design, a design that combines closely spaced beams and corrugated steel walls is the best solution.
With so many options of blast-resistant modular buildings to consider, it is always in your interest to review all the details and recommendations and consider your options. This way, you can take a final informed decision.
RedGuard has always relied on third-party engineering in many years of research and testing of blast-resistant designs. Thus, all the designs of blast-resistant modular buildings at RedGuard Specialist Services include all of the important elements mentioned, including the redundant steel beams and the corrugated steel that will flex a minimal amount to absorb most of the blast wave.