Across a range of industries – oil and gas, pharmaceuticals, and manufacturing to name a few – facilities and infrastructure must routinely operate under extreme conditions of temperature and pressure. Though professionals in these areas typically exercise due care and take the necessary precautions, incidents can and do occur, resulting in ruptures and localized explosions or blasts. Here, we explore why structural steel is the most suitable material for blast resistant buildings.
Why Blast Resistant Structures Are Necessary
Blast resistant buildings are structures which are designed to withstand explosions in hazardous environments, so that those who work inside them can make it home safely each night. You’ll sometimes hear these structures referred to as blast-resistant modules, blast-resistant units, or simply as a BRB (Blast Resistant Buildings) or BRM (Blast Resistant Modules).
The typical construction of a blast-resistant modular building consists of thick walls of steel, which are capable of withstanding high levels of blast pressure. There are sound scientific and structural reasons for this.
Why Steel Is the Ideal Material for Blast Resistance
Steel is a metallic alloy that basically consists of iron combined with small amounts of carbon. The addition of a small amount of non-metallic carbon to iron swings the qualities of the resulting material away from the metal’s natural ductility or ability to be stretched or hammered into wires and sheets, towards greater strength. In fact, the ultimate tensile strength or resistance to pulling action of low-carbon steel is between 400 – 550 MPa (around 58,000 to 79,750 psi). Very high strength steels can have an ultimate tensile strength as high as 3,000 MPa or around 435,000 psi.
These ultimate strengths for steel can be as much as 50% to 60% higher than its yield strength – the point at which the material begins to deform plastically. Beyond this, yield stress is the yield point, at which nonlinear elastic and plastic deformation begins. When a structural steel experiences stresses in excess of its yield point, it will suffer a small percentage of permanent deformation when the stress is reduced.
In a blast-resistance context, this means that buildings made with structural steel may undergo some deformation under the effects of a strong explosion – but the critical thing is that they won’t collapse or fail. Deformation may occur under tension or compression, without catastrophic failure.
When a blast wave impacts the surface of a steel blast-resistant building, the steel walls are known to move a minimal amount, sometimes referred to as “flex.” This minimal movement absorbs the energy of the blast wave and protects the building’s occupants. Other building types, particularly precast concrete, are rigid and don’t flex like steel. Instead, they rely only on the strength of the building material.
Strong, blast resistant steel buildings also don’t need to be as bulky as their concrete counterparts. Although steel has a large bulk density, it possesses much higher strength than other construction materials, so when the loading and environmental conditions are the same, a steel structure will be lighter than structures made of concrete or other materials. Steel structures also exhibit good sealing performance, making them ideal for the fabrication of high pressure vessels, pipelines, and shells.