Building components · Frame Members
Gusset Connection
Explains the gusset as a node where members arriving at different angles are made to work together, and why the geometry of that node matters.
Educational reference entry. What this element has to do, and whether any particular arrangement of it is adequate, depends on the whole assembly, the loading, the exposure, local requirements, the manufacturer's instructions and qualified professional design.
Overview
What a gusset is
Where several members arrive at one point at angles to each other — the chords and webs of a truss, the diagonals at the corner of a braced bay — the forces cannot pass directly from one member into the next. A plate is introduced that every member is fixed to, and the forces enter the plate, change direction within it, and leave through the other members.
The geometry of the node is part of the connection rather than a drawing convention. Where the centre lines of the members meet at a point, the forces balance at that point; where they do not, the offset introduces bending into the plate and into the members, which is why node setting-out is a design matter rather than a fabrication convenience.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a splice connection. A splice continues one member in its own line, and only one member is present; a gusset joins several different members arriving at different angles, and its job is to turn their forces rather than to continue any one of them.
- It is not a structural bearing. A bearing is the condition of support where a member rests on something and its load passes downward through the contact; members can hang from a gusset in tension as readily as push into it, and nothing is resting on anything at a node.
- It is not a column base plate. Both are plates in a steel frame, but a base plate spreads one column's load into a foundation beneath it, while a gusset gathers the forces of several members meeting at a node within the frame and passes them between each other.
Terminology
Common names and aliases
These names describe the same element. The library keeps one entry per component so that a trade term or a regional name never becomes a second, thinner page.
- gusset
- gusset plate
- node plate
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- Whether the centre lines of the members meet at a point, since an offset node puts bending into members that were arranged to be pushed or pulled along their length.
- The arrangement of bolts or welds connecting each member to the plate, because each member's whole force passes through its own group of them.
- Restraint of the plate itself where members push into it, since a plate being pushed on can buckle just as a member can.
- Access for making the connection and for looking at it later, which differs sharply between a node fabricated in a shop and one assembled at height.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
Every force arriving at the node passes through the plate, so the gusset is the load path rather than a piece holding members in position.
Several members have to arrive in the positions the node was set out for, and small differences in angle or position at a node are not local — they change what every member at it is doing.
Faces clamped together at a node hold moisture where it cannot dry, and the condition of a connection between plate and member is not readable from the outside of it.
Nodes assembled at height are made under conditions very different from those in a fabrication shop, which is why what is shop-made and what is site-made is part of the design.
Materials
Commonly formed from
Material families this element is commonly realised in. This states common practice only — it is not a statement that any of these materials suits this component in a particular building, which depends on the whole assembly and on qualified review.
Assemblies
Building systems this element is met in
The role this component fills inside each assembly. A role describes what the element does there — it is not a statement that this component suits that system in any particular building.
Clarifications
Commonly misunderstood
- That the gusset is a plate holding members in place while they do the work. It is the work: every force arriving at the node passes through it.
- That the pressed metal plates at the joints of prefabricated roof trusses are incidental ironmongery. They are the connection, and a truss with a lifted, corroded or damaged plate has a damaged load path.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- Do the member centre lines meet at a point at this node, and what was assumed about that?
- What force does each member deliver into the plate, and through what fastening?
- Is the plate restrained where members push into it?
- Will this node remain accessible for inspection after the works around it are finished?
Go deeper
Related Build Design Hub guides
Planning guidance behind the decisions this element involves.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this element comes up.
What this entry does not do
- This entry describes a connection position. It states no plate size, bolt arrangement, weld specification, capacity or fire rating, and none can be inferred from it.
- Where the centre lines of the members meet, and what each fastening group at the node has to carry, are qualified design decisions, and the condition of a made node is assessed by inspection rather than deduced from the members meeting at it.
Structural Frame Members
The columns, beams, joists, rafters, plates and bracing that make up a load-carrying frame, identified by the position each occupies.
Browse all frame members entries →