The Importance of I Beams in the Construction Industry
07 November 2023
Structural steel spans many unique products and materials. Steel beams are arguably one of the most recognisable and frequently used products, particularly universal beams. You may have encountered these at some point, either during construction or afterwards.
Universal steel beams are frequently called I beams due to the unique shape of the cross-section shape. This comprehensive guide explains why many builders and engineers use these products for their projects and tells you everything you need to know about using I beams in construction.
Structural Steel Beams
The I beam is widely used in domestic, commercial and industrial applications. It’s also frequently misinterpreted as an RSJ (rolled steel joist), a popular colloquial term for this product. The industry definition is a universal beam, and when people generally refer to an RSJ beam, this is the product they’re talking about.
Builders and engineers use I beams in construction projects due to their diverse range of uses and how practical and structurally advantageous they are. They can take various shapes, sizes and dimensions, which is critical for any person requiring structural steelwork to understand.
Steel I Beam Shapes
The universal I beam consists of two horizontal plates - flanges - connected by a vertical component, the web. The shape of the flanges and web form an ‘I’ or ‘H ’-shaped cross-section. I beams are mostly made from structural steel, although other metals such as aluminium, stainless steel and carbon steel (mild steel) can be used.
People can buy steel I beams online in various sizes and specifications, where they have the option to determine web thickness, flange length and section depth. Understanding this is essential as builders would order steel beams based on the requirements of their project.
When a builder orders steel online, I beams would be split by various number combinations. For example, a 127x76x13 UB (S355) would detail the web length, the flange length and the thickness in millimetres. The S355 figure describes the grade of steel used, which can vary across steel fabrication companies.
But builders have to take the following into account when they buy steel:
- Deflection - the beam must be thick enough not to deform.
- Vibration - there needs to be as little vibration as possible.
- Buckling - the flanges should prevent buckling from all angles.
- Bend - the steel beam cross-section should accommodate yield stress.
- Tension - the web shouldn’t buckle or ripple under pressure.
Due to these structural steel beams’ unique design, they can bend under high stress without buckling. This is why the axial fibres within the beams contain most of the material and where most of the force is directed.
Why Are I Beams I Shaped?
The ‘I’ shape of an I-beam, also known as an H-beam, universal beam, or double-T, results from a design that maximises its efficiency in resisting bending and shear loads.
Crucially, the I shape of the I-beam efficiently distributes material where it's most needed to resist the typical forces it will encounter. This optimises the balance between strength, weight, and material cost.
Uses of I Beams
Structural steel I beams have several uses across the construction industry. They generally comprise the main framework in many buildings, offering consistent, resilient and relentless support. They make the building framework so stable and robust that there often doesn’t need to be many steel support structures installed, thereby saving time and money in the long run.
Universal beams have a high level of functionality, with their unique shape making them perfect for unidirectional bending parallel to the web. The flanges help the steel beam resist bending, while the web supports shear stress. I beams can support heavy loads without succumbing to buckling, so it goes without saying that if you need structural support, use an I beam.
What’s more, universal beams have a unique design that doesn’t use excessive amounts of steel to manufacture. Very little - if any - waste is used during manufacturing, which is handy when you recognise how environmentally friendly and sustainable structural steel is.
What are I Beams used for?
I Beams, also known as H-beams, W-beams (for "wide flange"), universal beams (UB), or rolled steel joists (RSJ), are used primarily in the construction industry as a structural component in buildings, bridges, and other structures. Their specific applications include:
Building frames
I Beams serve as primary support trusses in the structure of buildings. They are used in the framework for bridges due to their strong bending resistance, and I Beams can also provide additional strength when setting the foundation for structures. In industrial settings, they can be used to create platforms and loading/unloading ramps, and I Beams are also used as rails for some overhead crane systems.
How are I Beams Manufactured?
I Beams are typically manufactured using two main processes:
Hot Rolling: in this method, rectangular billets or steel slabs are heated to a high temperature and passed through a set of shaped rollers, moulding the heated steel into the desired I Beam shape.
Welding: I Beams can sometimes be manufactured by welding together three steel plates to form the I shape. The vertical section is called the “web”, while the horizontal sections are called “flanges”.
Key Features of I Beams
Shape: An I Beam has a cross-sectional shape resembling the letter 'I'.
Web: The vertical or central section of the I Beam.
Flanges: The horizontal sections at the top and bottom.
Strength: Due to their geometry, I Beams are solid in terms of bending and shear loads.
Weight Distribution: The I shape ensures that most of the weight and resistance is located at the top and bottom, providing optimal bending resistance.
How Much Do I Beams Cost?
The cost of I Beams can vary significantly based on several factors:
Material: steel is the most common material, but its grade and quality can influence the cost.
Size and length: larger and longer beams generally cost more.
Supply and demand: prices can fluctuate based on market demand, availability, and other economic factors.
Geographic location: costs can vary depending on transportation, tariffs, and local market conditions.
Manufacturing process: welded I Beams might have a different cost than hot-rolled ones.
For specific pricing, it's recommended to contact local suppliers or manufacturers.
What is the Difference Between I Beams and H beams?
While both beams look quite similar, and the terms are often used interchangeably, there are some subtle differences:
Flange width and thickness: I Beams typically have tapered flanges that become thinner further from the web, whereas H beams have flanges of equal thickness from the centre web to the outer edge.
Cross-sectional shape: I Beams have a somewhat narrower flange width relative to their height, while H-beams have a more squared appearance.
Applications: the choice between the two often depends on specific design considerations, weight distribution, and the application's structural requirements.
Despite these differences, in many instances, the choice between the two can come down to regional terminology and preference.
High-Quality Online Steel Fabricators and Suppliers
Buy A Beam is a one-stop-shop for anybody who requires high-quality steel beams from reliable, CE-approved structural steel fabricators. Buying steel online has never been more straightforward than with Buy A Beam.
Simply enter your postcode to find a nearby steel fabrication facility; if there’s more than one, you can choose which works best for you. From there, you can browse a wide range of steel products. You’ll have options to add web or flange holes, steel plates on the top or bottom of your beams, and much more.
If you need something more specific and bespoke, such as a steel frame building constructed in kit form, you can also request that. Alternatively, speak to the team to see how we can help. We’re here to help you with any queries on structural steel fabrication and products.