Discover the benefits of composite floor joists
Are you familiar with composite floor joists? Despite the preconceived notions surrounding these multi-storey building components, they are increasingly common in North America. In fact, they offer numerous advantages, especially in terms of building mechanics and work schedule.
Composite joists are in fact open web steel components on which a steel deck is affixed to support the floor (or roof) of a building. Studs are welded onto the joists and the steel deck, interconnecting them with the concrete slab once it is poured. In this type of assembly, studs allow the concrete slab to work together with the steel joists to support loads. As a result, the structure benefits from both the significant compressive strength of concrete and the excellent tensile strength of steel. Furthermore, studs also increase the bearing capacity of steel decks.
Composite floors are perfect for long span structures, from warehouses to distribution centres, including several types of industrial and commercial multi-storey steel buildings.
For example, composite floors help reduce the number of columns while maintaining an optimal bearing capacity, allowing you to build a warehouse mezzanine and thus maximize the building’s height. Furthermore, the concrete is taken into account when assessing the building’s overall resistance, as it is an integral part of the structure.
Although composite beams are usually easy to find and manufacture, they may not be as readily available when dealing with a shortage of materials. For this reason, opting for joists when building your warehouse mezzanine can provide better adaptability while reducing the weight of structural materials by close to 45%.
More often than not, non-composite systems do not take full advantage of the structure’s concrete, which is simply poured onto the steel deck without being anchored into the steel structure with studs, as is the case with composite joists. Although they require less calculation, non-composite systems also fail to take advantage of a building’s various structural elements, nor do they increase the bearing capacity. Furthermore, they require heavier components to make up for the inferior bearing strength.
Adding a concrete slab is a common option for multi-storey buildings. This sturdy solution can, however, be more costly. Moreover, the foundation may require reinforcement because of the added weight—and the differences between steel and concrete do not end there!
Structures built using joists are widely different from those made of concrete and offer several benefits.
Do you wish to optimize an open space? Joists provide spans ranging from about 12 to 21 metres (40 to 70 feet) without affecting the building’s performance. These large column-free areas offer increased layout flexibility, providing enough space for warehouse robotization or to easily reconfigure the leased units of a commercial building.
Lighter and less wide, joists can support the same load as other methods, allowing you to comply with building standards while using fewer materials. Since they reduce the floor’s depth, joists can also reduce a building’s height. By focusing less on foundations and ground reinforcement, you limit costs and speed up on-site assembly.
As you know, the cost of steel, which is priced according to weight, has recently skyrocketed. Composite floor joists are therefore perfect for tight budgets, as they minimize material costs.
Since composite floor joists are not solid, they can more easily accommodate building mechanics (which can be passed through the joists) while optimizing its interstitial spaces. Indeed, these types of joists do not need to be bypassed or drilled through and then reinforced in order to run pipes, cables, and metal ducts. They require fewer connections and reinforcements, which minimizes on-site assembly time.
Furthermore, the distance between each joist allows the structure to adapt to the various life cycles of a multi-storey building, whether dedicated to industrial, commercial, or office use.
Composite floor joists can be placed further apart, requiring fewer columns and heavy components that can only be lifted with a crane. This helps fast-track the assembly while minimizing the impact on the overall schedule. Although stud installation represents an extra step, the procedure can easily be optimized: they can be welded at night by a smaller team or installed when it is too windy to operate a crane. In truth, this step does not prevent joists to be installed within the same timeframes as other types of structures!
Depending on your needs, this floor support option may be suitable for your project. Although less common, this method holds no secrets for us! Our team of experts can help you make the right choice and assist you as early as the calculation stage all the way to assembly.
To find out more about the author, we invite you to view Sébastien Paré’s LinkedIn profile.