Composite Steel Frame: A Brief Overview

Part of the draw of steel as a construction material is the combination of availability, versatility, and durability. Perhaps nothing sums up all three of these traits like a composite steel frame. By implementing the properties of steel along with the properties of concrete, you have a piece of construction that is uniquely suited to the rigors of high-traffic structures like buildings and bridges.

 

However, if you are a new steel contractor that is just starting to branch out their services, how do you find out if composite steel frames are the right fit for you? 

 

Here’s a closer look at what exactly a composite steel frame is, installations where it is commonly used, and how you can get the most out of it.

 

What Is A Composite Steel Frame?

 

Composite steel frames are one example of the concept of composite construction. Essentially, what this means is creating a structure from two different materials, bound so tightly together that they are essentially a single item. Composite steel frames are one of the most common examples, bringing together steel beams with a concrete floor slab.

 

Let’s say that you simply set a floor slab on a steel beam loosely.  The slab would transfer all its weight to the beam, but wouldn’t actually improve its load-carrying capacity. This changes when you add studs to connect the slab positively with the beam. Suddenly, both elements become one element and are a lot stronger and can handle larger loads. This is what makes composite steel frame cross-sections so useful.

 

So, with that said, how exactly does the process go into practice? 

 

By and large, it starts with implementing steel decking. Specially formed decking, combined with concrete fill, it allows for a stiff and lightweight flooring system to put on top of your steel beams.

 

The decking is set on structural steel at different points in the erection sequence, either by the steel contractor or separate decking one. This can be done either through powder actuated tools or welding.

 

The next step is implementing shear studs to actually connect the decking to the structural steel. These studs create the bond between the beam and floor slab which will be poured on later, lowering live load detection.  

 

When the decking is installed, shear connectors are attached next. This requires specific spacing to make sure that the slab doesn’t get separated from the beam, or put too much pressure on a specific part.

 

When this is completed, it’s time to install the concrete on top of the composite metal frame. Generally, this is done by a concrete contractor, unless you are a general contractor who already has concrete professionals on the job.

 

Key things to focus on when pouring the concrete is applying it to supporting areas before the midspan of the deck, and avoiding any deep concrete piles.

 

Ideally, shoring should go under the joints until the concrete gets to 75% of its strength. This ensures that there won’t be any bond failure between concrete and metal.

 

Finally, the area will be inspected by a supervising engineer.

 

composite steel frame

Photo By northlight

 

Pros And Cons

 

Before you decide to add a composite steel frame to your list of services, though, you also need to be able to communicate the advantages to potential clients. Here’s a rundown of the major benefits:

 

The cost of your structural steel frame overall is going to be lower than non-composite steel installations.

 

You get to save in time and labor costs. This is largely due to the fact that the composite deck is both the form deck and positive reinforcement for the finished structure.

 

If you use cast-in-place steel construction, you lose a lot of time on shoring repeatedly. You don’t have to worry about this with most composite construction.

 

Because the composite steel frame weighs less, foundation costs are lower.

 

Composite steel frames have better live load deflection and vibration performance. This is because they are stiffer overall.

 

You have the potential to use shallower composite beams. This gives you the chance to reduce building height if needed.

 

There’s the potential for a larger span length.

 

Equally important is making sure that you can address some of the issues with composite steel frame construction. These factors may drive your potential customers to use one of your other steel installations:

 

If you compare this to a cast-in-place concrete system, this is going to be more expensive. Granted, a composite steel frame can do things a cast-in-place concrete system can’t.

 

If you decide to use shear connectors, you’re going to need to use automatic stud welders. This generally requires specialized subcontractors.

 

If you opt to use a camber, it may be hard for you to keep the concrete level. 

 

Knowing these potential areas of weakness means that you can address the issue before your clients bring them up. However, creating and implementing a composite steel frame is far more complex than typical steelworking. Not only are you doing all the work of a normal steel installation, but you may be looking at multiple other contractors to handle the concrete and stud work.

 

composite steel frame

Photo By Ocsi Balazs

 

Understanding all the forms of composite steel frames and the aspects of composite construction are essential to any steelworker or steel contractor. The next stage of mastery is figuring out how to do composite steel jobs as effectively as possible. Your best tool in this endeavor is data. Data shows you how much items like composite beams cost so you can price your services effectively. Data will also show you the best practices and directives to give to your teams during composite action.

 

To extract the data you need as well as communicate information from the office to the worksite, you need composite steel frame project management software. eSUB is a standout here. We give you all the information you need to power your decisions, while also making it easy to share information and directions between different teams. 

 

Construction Software