Architectural steel is the most common material used in building projects around the globe. A major reason behind architectural steel’s popularity is the low cost of manufacturing. The raw materials of architectural steel, iron ore and scrap, are in plentiful supply to us. Manufacturing, forming, and processing steel is cheaper than almost any other building material. This fact alone puts it head and shoulders above any other building resource.
The United Kingdom is the tenth largest producer of steel, but this only accounts for 0.7 per cent of world production.
Architectural metalwork projects are a great triumph of mankind. Think of the effort behind the building of long-lasting bridges and creative skyscrapers. How was this achieved? Over time, architects and engineers have responded to many different challenges. Now there are many different forms of rolled steel sections to meet most demands.
‘Alphabet structures’ get their name because the flanges and webs resemble various letters put together. Each ‘letter’ has its own purpose in the construction world. Some are more common than others.
L-shaped ‘Angle’ beams
Angle, ‘rolled steel angle’, or ‘L’ shaped beams consists of two legs that come together, meeting at a 90-degree angle. The leg sizes may or may not be of equal size, depending on the requirements. This splits the L-shaped beam into two camps: equal and unequal. ‘Equal’ angle beams are usually used for structural steel brackets and cleat connections. ‘Unequal’ angle beams are often used as lintels, and commonly in floor systems.
C-shaped ‘channel’ beams
These beams can be referred to in many different ways as ‘channel’ beams; ‘parallel flange channels’, and C-section beams. The Channel is used for columns, lintels above doors to give support to floor joists. If you are using a Channel as a lintel it will need a bottom plate added to it to take the outer bricks, alternatively, 2 Channels could be fixed back to back to support both leafs of a cavity wall.
Universal Columns: ‘H’ and ‘I’ beams
Universal Columns are the most frequently used section for construction their small depth makes them ideal for load bearing when height is limited. Due to their shape, they are often referred to as “I sections” or “H Sections”. The Universal Columns width is usually roughly the same as its depth.
Just to add confusion both Universal Beams and Universal Columns are also referred to as “I sections” or “H sections” the difference is easy to spot as the depth of the Universal Beam is greater than its width. The advantage of the beam is that it has a higher loading capability, however often space is an issue and therefore a column would be used.
Both ‘H’ and ‘I’ beams are capable of resisting shear forces and are extremely resistant to bending.
T beams can withstand large loads but do not have the bottom flange that would make it an ‘I’ beam. They are often used in steel roof trusses to form built-up sections. The lack of a bottom flange is cost-effective in terms of needing fewer materials, but there is a trade-off. T beams are not as strong as their I-beam equivalents.
Rectangular, square, and circle sections
In Britain, these sections are abbreviated to RHS, SHS, and CHS. In the USA, they are known under an umbrella name as Hollow Steel Sections (HSS). These metals are hollow and tubular. Engineers use such sections where structures experience loading in different directions. Rectangles, squares, and circles are the most common shapes, but with the latest technology, almost any shape can be made by a leading manufacturer with skilled fabricators for any purpose. To get an idea of what can be done, check out our blog here.
RHS (Rectangular Hollow Section)
The rectangle shape is quite hard to bolt. For this reason, it is not as common as the Universal Columns (see above). It is hard to bolt and to bolt other members or beams to it. There are two types of RHS: ‘hot’ and ‘cold’. Hot rolled RHS sections consist of one piece, right off the mill. Cold-formed RHS sections need welding together and are not made in one piece.
SHS (Square Hollow Section)
Like the RHS sections, square hollow sections are difficult to use. It is hard to bolt them to beams. SHS also come in ‘hot’ and ‘cold’ forms. Another name for them is a “box section”.
CHS (Circle Hollow Section)
CHS is popular for the construction of handrails, balustrades, and scaffolding. Other purposes include sign poles, columns, fences, and architectural features such as bending steel staircases. CHS can be fin controlled and internally scarfed. This allows the tube to be suitable for mandrel bending.
Flat Sections are used anywhere a connection between two beams is required. Flat sections are used as base plates, end plates, stiffener, tabs, gussets, and splice plates. When a Flat section is cut into smaller pieces it is called a plate. Flat sections are often used to strengthen other beams and are sometimes used to reinforce timber joists.
The word ‘beam’ can have many different meanings and used to refer to a solid piece of timber. In building construction, a beam is like a mini bridge in a structure that carries a load. The load may be a brick wall or the floor or roof of a building.
As its name suggests: a crossbeam is a type of beam that runs ‘across’ a structure, carrying its load. This is in opposition to other ‘beams’ that support a structure upright. In mechanical engineering, this can be a little confusing. There is little differentiation between a beam and a crossbeam. Even dictionary definitions can sometimes refer to a ‘beam’ as a horizontal support.
‘Goalpost’ beams get their name from their shape. When two columns and a crossbeam come together, it looks like a goalpost. It is an unimaginative but unambiguous name.
Goalpost beams are often used where the foundations can be dug and cast in concrete (such as rear extensions). Goalpost beams are very sturdy. If a project requires a large aperture (an opening or hole) then goalpost beams are ideal. Their columns are well-designed to dissipate the load.
Goalpost with cross beam
A crossbeam is a beam placed between two walls in a structure; in most cases to support the roof of a building. A goalpost beam is often used with a crossbeam if the crossbeam has replaced something in the existing structure.
Goalpost with 2 cross beams
If two walls need supporting, it may be necessary to use a goalpost beam along with two crossbeams.
Two goalposts with cross beam
Take two walls out, and there can sometimes be load issues. Two goalposts and a crossbeam provide a structurally-sound solution to support remaining walls.
A crossbeam is typically made from a steel I-beam, and is able to support an enormous amount of weight over a very long timeframe.
Cross beam with two beams
This metal structure is particularly good at supporting chimney stacks. The cross beam takes the bulk of the weight, while the parallel beams span the sides of the room. A top plate is sometimes added to distribute the weight of the chimney.
Crank with crossbeam
If there is a ceiling, there’s likely to be a crank with a cross beam. This structure is adept at supporting roof joists.
Crossbeam with mid support
Modern support columns may not be as glamorous as the ones used in Ancient Greece but they are just as sturdy. If the load of a crossbeam is in need of support, then a mid-support column is usually the answer.
Note: mid-support columns need to fit in-between windows, doors, and other walls.
Beams carry the weight of the developed world. Beams carry loads by bending (a process known as ‘flexure’). There are many different types of beams. Each slightly modified to accommodate the dynamic world of architectural steel.
This structure gets its name from its double-cranked shape. The two cranks draw on the main beam for strength. Often the apex beam is the structure of choice in floor renovation.
Post with beam
A post with a beam is often used for extra support. Typically this is when one beam has the support of a load-bearing wall and the other does not.
Beam with mid support
Sometimes the load on a beam may be too high. In such instances a post will add extra support, taking the weight off the beam. The post’s final position will depend on the layout of the room, so it may not always technically be a ‘mid support’.
Corner beams with post
Corner beams with a post are there to buttress both rear and side walls. They are usually present in structures such as extensions.
A ‘box frame’ is a reference to the square shape made when four beams come together. There may be steel beams running parallel in the side walls; one on top and one on the bottom.
Box frames with crossbeams
A crossbeam is a beam placed between two walls in a structure; in most cases to support the roof of a building. A box frame is often used with a crossbeam if the crossbeam has replaced something in the existing structure.
Box frames with a beam and post
A steel post may be necessary if there is nothing to support the box frame after construction. In the absence of a load-bearing wall, the burden shifts to the post and its foundation.
Box frame with perpendicular box frame
If the load is particularly heavy, then a post on its own may not be enough to carry the weight. In such instances, a bottom beam is usually added: that connects the post to the foundation of the box frame. This serves to spread the weight around, shifting the burden from the post.
Two box frames with a cross beam
In some instances a structure may need two box frames joined with a crossbeam. For example, it is not uncommon for a wall to be ‘knocked down’ to create larger living space. With the wall gone, a crossbeam is sometimes needed to manage the load.
Box frames with extended beams
An extended beam is often used when there are space limitations and a column is not an option. The extended beam distributes more of the weight. Box frames with extended beams are often used in the corridors of large buildings.
It is incredible to think that it is really metal connections that hold society together. They provide support for the joints and foundations of our mightiest, tallest buildings and everything in-between.
Base plates are what supports a column on its foundation. For stability and lasting power, it is essential to fix a base plate about 20mm above the concrete around the column. Wedges and metal shims can force open a gap, which is then filled with dry-pack (a type of concrete).
An end plate is much like a base plate, but acts as an anchor to a wall, not the floor.
End plate connection
Like its name suggests, end plate connections help connect two points. This may be two beams or a flange.
In construction, the term ‘moment’ refers to the amount of stress on a joint. Moment connections are there to help reduce the pressure a joint may be under. An overhanging plate bolts into both columns, reinforcing its strength.
A cleat bolts two beams together (though in some cases it may be preferable to weld the cleats, depending on the circumstance). It provides strength and reinforces connections at the beams.
Also known as ‘rebar spacers’. Spacers are sometimes made of concrete, metal — even plastic. The spacer reinforces the steel by keeping it in place. This is important for the final pouring of concrete into the structure.
Spacer beams are often used to bolt two beams together, giving both rigidity and security.
A PFC space — as the name suggests — is often used to bolt two PFC beams. (A PFC stands for ‘Parallel Flange Channel’.) After bolting two PFC beams back-to-back, a PFC spacer is there to give strength to the walls.
Cranks and Kinks
Cranks and kinks are essential components to architectural steel.
A characteristic crank with two notable kinks. Ninety-degree cranks support roof structures. Supporting the roof is very important. Thus, it is important to conduct full penetration welds when manufacturing these cranks. A penetration weld is a weld that penetrates fully from the roof of a joint (top) to the cap (bottom).
A ninety-degree kink is the basic shape of two sections welded together. These kinks are common in brackets and to bolster support for columns.
This angled kink follows the shape of the roof. It reduces the load burden on the crossbeam. It can do this without the need for extra vertical support columns.
Kink with plate
A plate is necessary for a kink angle if the connections are of different sizes. The plate allows the two sections to join together.
Often used for supporting a staircase.
These brackets are antiquated. Some local authorities no longer permit them — in which case a full beam structure is the only real alternative. Traditionally, gallow brackets are in place to support chimney breasts.
Plates are the joining forces of the architectural steel world. They are often the last part of the construction puzzle designed, yet one of the first installed. They are often made from the cutting of flat sections and then welded to joists.
Gusset (a triangular plate)
A gusset is a triangular-shaped plate. The shape of which allows extra sturdiness to the structure. In many cases, gussets act as extra support for bottom plates welded to a beam.
Bottom plates give beams that extra support to keep brickwork and timber joists in place. Bottom plates often ‘stick out’ under the beam. This is to make sure the support is adequate.
A top plate, like the bottom plate, is there to increase support for the beam. Top plates are sometimes used if the size of the required beam is smaller than the wall it is carrying.
Stiffeners are there to provide extra stability and prevent buckling.
If a column section needs anchoring to a wall, which is where a tab comes in. Tabs are welded in a staggered formation to column sections to give them an extra rigidity.
Holes are often drilled strategically in architectural steel to bolster support and structure.
Flange holes are an alternative to using tabs. As the name suggests, flanges often have holes drilled into them for extra rigidity.
Web holes are ideal for fixing timber joist hangers to beam joists. This is often necessary for the laying of floor joists.
Splices exist to join two members end-to-end in construction. Splices come into force if the existing structural elements require longer lengths not available. They ‘bridge the gap’ in effect, to compensate for this lack of availability.
A splice is required when a beam spans two party walls for ease of installation, or, when a beam of either too long or too heavy to install.
If the splice connection requires extra, inner flange plates, it goes by the name ‘splice A2′.
Is used to align two sections and would need additional support either with a column or pad stone.
The splice B1 is a good choice in space-restricted areas. It is not a full splice, and so may be unsuitable in some applications, but it is a considerable space saver.
Metal finishes help to prevent rust. Rust is the end-process of a chemical reaction. And although ferro-alloys are added to steel, it is not always enough. When moisture and oxygen comes into contact with steel, molecules join to form iron oxide. This makes the metal weak, corrosive, and useless.
The slowing or prevention of rust is big business. Because so much of the world uses iron and steel, it is of major importance to keep our architecture healthy.
Priming (Primed Steel)
A primer is a coat added to steel to stop it rusting. This is usually done before painting the steel. It is common in maritime, and highway and infrastructure industries.
The primer itself is often a ‘paint’ of resin, additives, and solvents. Some primers even contain plastic polyethylene. Primers keep painted steel fresher for longer, because the primers used help the paint-coatings stick around.
Galvanising (Galvanised Steel)
Galvanising is the process of applying a zinc coating to steel. A bit like with stainless steel. This can protect the steel from atmospheric corrosion for more than 30 years. There are two general applications for the zinc coating: hot dipping and electrolytic deposition.
The zinc coat often ‘sacrifices’ itself to keep the steel intact, as the chemical makeup of the zinc makes it more likely to corrode. Galvanising is a common and essential part of steel fabrication, especially in the cladding industry. It is very useful for keeping steel intact, especially in external and damp areas. But also for inside walls susceptible to where moisture can enter.
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