Steel Sections

Universal columns

One of the most used sections in structural steel a universal column also known as a ‘H’ Beam or ‘I’ Beams, due to their shape. UC’s are mainly used as horizontal columns in buildings to carry compression loads. They might transfer loads from a ceiling, floor slab, roof slab, or from a beam, to a floor or foundations. They are mainly disguised within the building structure being plastered over but can be featured in industrial buildings.

Universal Columns are mainly used in conjunction with connections and universal beams to create full structures but can be needed individually where a span of a building is too large to go unsupported.

Universal Columns can be identified by the width and depth being roughly equal. In practical terms allows the minimum amount of space to be taken up in comparison to the weight that is borne onto the column. This also means that universal columns are sometimes used instead of universal beams where ceiling height is limited and needs to be maximised.

Universal column sizes are displayed as 152 UC 30, where the 152 shows the beam is 152mm wide and 152mm deep. The last number (30 in this example) is the weight per metre in kilograms. It is therefore easy to work out what is the total weight of a UC by simply multiplying its weight per metre by the total length in metres.

For ordering UC’s you can use our easy chart and diagram below.

Universal beams

Also know as RSJ’s, ‘I’ Beams or ‘H’ Beams universal beams are the probably the most common steel section used in residential projects. Used vertically, in-between floors or horizontally in ceilings to carry and support the weight of the above load equally to stop collapse. Universal steel beams have overtaken more traditional wooden beams due to the longevity and strength of the material, simply put steel beams last and can create spans and take weights that other, more traditional materials simply could not. And it can do all these whilst taking up the minimum amount of space and can be hidden within a buildings structure, in ceilings, meaning you don’t have to see the structural beams, unless you want to!

Universal beams can be easily identified by their greater depths compared to the widths (see diagram). This increase in the depth creates a stronger structure to carry greater loads over spans.

Universal beam sizes are displayed as 127 x 26 UB 13, where the 127 shows the depth of the beam and 26 the width. Therefore, in this example beam is 127mm deep and 26mm wide. The last number (13 in this example) is the weight per metre in kilograms. By multiplying the total beam length in metres by the weight per metre we can quickly work out what is the total weight of the beam.

For ordering UB’s you can use our easy chart and diagram below.

Parallel flange channel

Also known as a ‘C’ Beam, PFC’s have a range of uses including columns, supports for floor joists or lintels above doors or windows. They are essentially a load bearing profile similar to UC’s and UB’s but their design shape allows for alternative applications. PFC’s can be mounted against other flat surfaces such as party walls to maximise contact area, and therefore strength, whilst saving space. They can also be used in cavity walls where channels are bolted back to back with 100mm spacers to support both leaves of brick work whilst ensuring minimum moisture transfer.

Parallel flange channels can also be bolted or welded back to back to create nonstandard beams or can be used when there is a limited space such as only one skin of brick work for a beam to sit on.

Ultimately a parallel flange channel can carry lesser weights compared to a UC or UB but its alternate design can be extremely useful in various situations. The weight capacity and design aspects will all have been taken into account by your structural engineer, so trust their knowledge on which beams are better for your project.

PFC are described as a variation of 100 x 50 x 10 PFC where 100mm represents the depth, 50mm represents the width and the final number (10 in this example) represents the weight per meter in kilograms.

Rectangular hollow section

Rectangular hollow sections (RHS) are mostly used as columns where a base plate and cap plate are attached to the top and bottom or where two beams are bolted in to either side. Although not as common as universal columns and beams RHS’s are often used for architectural aesthetics due to their clean lines working alongside their structural strength.

There are two main types of rectangular hollow sections; cold rolled and hot rolled. Cold rolled sections are rolled from a flat sheet into right angles and then welded at their meeting point. Hot rolled sections are formed into shape at the mill so the strength of the column is equal throughout, and higher overall than cold rolled sections.

RHS sizes are displayed as 50 x 25 x 2.5 RHS, where 50mm is the depth, 25mm is the width and the final measurement, 2.5mm in this example, is the wall thickness of the material.

Handy Tip – Hot and cold rolled sections come in common lengths so be sure to specify if you need hot or cold rolled when you are ordering! The two have different load capacity so one will have been specified over the other by your structural engineer.

Square hollow section

SHS’s also known as box sections are square formed hollow columns. Similar to RHS’s they can be used as columns where a base plate and cap plate are attached to the top and bottom or where two beams are bolted in to either side. Although not as common as universal columns and beams SHS’s are often used for architectural aesthetics due to their clean lines working alongside their structural strength.

There are two main types of square hollow sections; cold rolled and hot rolled. Cold rolled sections are rolled from a flat sheet into right angles and then welded at their meeting point. Hot rolled sections are formed into shape at the mill so the strength of the column is equal throughout.

RHS sizes are displayed as 20 x 20 x 2 SHS, where 20mm is the equal depth and width of the square and the final measurement, 2mm in this example, is the wall thickness of the material.

Handy Tip – Hot and cold rolled sections come in common lengths so be sure to specify if you need hot or cold rolled when you are ordering! The two have different load capacity so one will have been specified over the other by your structural engineer.

Circular hollow section

Circular hollow sections or ‘CHS’ are most often used to create additional strength. They can be used as columns or beams where force or weight bearing is extreme or comes from multiple directions but as their shape creates difficulty when trying to attach to other sections they tend to mainly be used as spacers between universal beams or columns. These spacer bars create a cavity between two beams but maximise the structural integrity of the frame.

Diagram of circular hollow sections being used as spacer bars between beams similar to bellow.

There are two main types of circular hollow sections; cold rolled and hot rolled. Cold rolled sections are rolled from a flat sheet and then welded at their meeting point. Hot rolled sections are formed into shape at the mill so the strength of the column is equal throughout.

CHS are displayed as 21.3 x 3.2 CHS, where the first number is the diameter of the circle and the second number is the thickness of the material (see diagram).

Handy Tip – Hot and cold rolled sections come in common lengths so be sure to specify if you need hot or cold rolled when you are ordering! The two have different load capacity so one will have been specified over the other by your structural engineer.

Flat section

Flat sections are probably the most diverse section in structural steel. They can be used for base plates, end plates, stiffeners, gussets, tabs, splice plates and many more. They are usually bolted or welded onto beams to connect the entire structure together. They can add strength to a beam when welded along the length, provide connections to other beams, walls and floors and can be welded to the bottom of universal beams to create a lintel where by the beam creates the base for the internal block work to sit on and the plate extends out underneath creating a base for the external brick work.

Flat section sizes are displayed as 40 x 3 flat where 40mm is the width and 3mm is the thickness of the material (see diagram). All flats come as standard in 6-meter lengths. Standard sizes are displayed in the below chart but if it is a smaller size you need then you will be looking for what is referred to as a “plate” which you will be able to find in connections.

Rolled steel angle-equal

RSA-e’s, sometimes referred to as “angles”, “equal angles” or “L-shapes” the ‘e’ refers to the equality of the angle with both lengths being identical. Rolled steel angles are used in larger lengths for framing purposes to create rigidity in a structure or can be used as lintels when two sections are bolted back to back. They are, however, most commonly cut into shorter sections and drilled to use at connections between perpendicular beams (see diagram).

Rolled steel angles are referred to using the format 20 x 20 x 3 RSA. Even though both legs are the same length, they are described by giving both leg lengths and the wall thickness (all in mm).

Rolled steel angles – U

RSA-u’s, sometimes referred to as “angles”, or “L-shapes” the ‘u’ refers to the unequal lengths of the angle section. Rolled steel angles and are mainly used in larger lengths for lintels as with the longer leg being in a vertical position, its loading capabilities are greater than equal angles. RSA-U’s are however, most commonly cut into shorter sections and drilled to use at connections between beams (see diagram).

Rolled steel angles are referred to using the format 30 x 20 x 3 RSA. Where the longest leg is described first in mm, the short leg second in mm and the thickness of the material as the last number in the sequence.