Services involved:
Extensions / Load Bearing Wall Removal / Loft Conversions / New Build /
What are Beam Splice Calculations & why they are important
In steel construction, end plate splices and cover plate splices are two common ways of joining steel beam sections together so they behave like one continuous member. They might look like just “connections,” but structurally they’re doing a lot of heavy lifting literally. We usually use splice connections primarily when designing the structural aspect for loft conversions. Due to access reasons/limited space it is often easier for the contractors to install the beams in discreet sections and bolt them together on-site to form one continuous beam. Our beam splice calculations contain the numbers and also fabrication specifications allowing the contractor to pass the calculation document straight to the steel fabricator for hassle free manufacture.
Beam Splice Calculations – End plate splices
An end plate splice uses a steel plate welded to the end of each beam, with the plates then bolted together on site. The end plate is typically shop-welded under controlled conditions, which is good for quality, and the site work is mostly bolting, which is fast and predictable.
Structurally, end plate splices can be designed as:
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Simple (shear-only) connections, where they mainly transfer vertical shear and allow rotation, or
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Moment-resisting splices, where the plate thickness, bolt arrangement, and welds are sized to transfer bending moments as well as shear.
In simple splices, the end plate acts as a force distributor, spreading tension and compression from the beam flanges into the bolts and across the joint. The bolts see significant tension, especially at the tension flange, so bolt grade, spacing, and prying action all matter.
End plate splices are popular because they’re:
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Quick to erect (less site welding)
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Repeatable and reliable
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Good for tight sites, where lifting long continuous beams isn’t practical
Beam Splice Calculations – Cover plate splices
A cover plate splice uses steel plates fixed over the beam flanges and/or web, spanning across the joint between two beam sections. These plates are either bolted or welded, depending on the design and construction sequence.
Cover plate splices are more traditional and very direct in how they work:
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Flange cover plates carry bending by transferring tension and compression across the joint
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Web cover plates carry shear
The load path is easy to visualise: forces simply pass from one beam, through the plates, and into the next beam. Because of this, cover plate splices can be very efficient for high moment or heavily loaded beams, we tend to use this method of splicing when supporting masonry loads.
The downside is constructability:
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More components
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More bolts or site welding
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More alignment control needed
But when designed and built properly, they’re extremely robust.
Why these splices are important
Steel beams don’t always arrive on site as one perfect length. Transport limits, crane capacity, phased construction, and future modification all mean beams often need to be spliced. The splice isn’t just a convenience it becomes part of the structural system.
Good splice design ensures:
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Continuity of strength and stiffness, so the beam behaves as intended in analysis
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Controlled deformation, avoiding unexpected rotations or slip at the joint
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Ductile behaviour, especially under accidental or seismic loading
A poorly designed splice can become the weak link, attracting damage, cracking, or excessive movement even when the beam itself is perfectly adequate.
Big-picture takeaway
End plate and cover plate splices are how us engineers “stitch” steel beams together. Done right, the beam doesn’t care there’s a joint there it just carries load. Done badly, the splice becomes a hinge, a crack initiator, or a failure point.
They’re not just connections. They’re structural elements that decide whether a steel member acts like a single, confident element or a collection of individual parts hoping for the best.