Structural Steel Detailing
Steel Connection Detailing Basics for Structural Engineering Projects
The geometry, bolts, welds and typical-detail decisions that turn a member layout into connections a shop can actually fabricate.
Connection detailing is where a clean framing plan becomes either a buildable frame or a pile of RFIs. The member can be the right size and still be undetailable if the connection has no room for bolts, welds or erection wrenches. This article stays on the detailing side of that problem: what must be shown, and which geometry decisions come first.
It does not replace connection design. Strength, ductility and the governing standard belong to the engineer who is assigned that work. If that person is not you, your job is to show the geometry they designed — or to stop and ask when the geometry will not fit.
For the surrounding workflow see what structural steel detailing is and common detailing errors.
Start with the workpoint, not the plate outline
Every connection has a theoretical intersection of member centre-lines or setting-out lines. Draw that workpoint first. Then place plates, bolts and welds around it. Drawing a plate that “looks square” and letting the workpoint fall wherever it falls is how accidental eccentricities appear.
- Show workpoints on bracing, truss and skewed beam details
- State any accepted eccentricity rather than hiding it in a tidy gusset
- Keep setting-out consistent with the analysis model if one exists
Bolts: diameter is the least of the information
A usable bolt callout includes diameter, grade, hole type (standard, short slot, long slot, oversize), thread condition if required, and whether the bolt is shop or field. Pretensioned versus snug-tight should follow the specification and the connection designer — do not invent a tensioning method in a typical detail.
| Bolt fact | Why the shop needs it |
|---|---|
| Hole type | Drilling/punching tooling and erection tolerance |
| Slot direction | Must match the intended movement or adjustment |
| Grip range | Bolt length depends on plies and washers |
| Access | A correct bolt that cannot be wrenched is not a connection |
Welds: size, type and the access to make them
Weld symbols without access are decoration. Fillet sizes must fit the thinner part and the process the shop actually uses. Complete-joint-penetration welds need preparation, and often inspection notes from the specification. If you are not the welding engineer, copy the specified symbol rather than “improving” it.
Copes, blocks and remaining section
Beam copes exist so flanges can pass. They also remove the section you were about to put holes through. Detail the cope to the fabricator’s standard where possible, then confirm that bolt rows and fillet welds still fit on what remains. Check flange and web thickness of the actual section, not a generic textbook sketch.
Typical details need a range of use
A typical simple connection that is valid from, say, a stated beam depth range should say so. Outside that range, force an exception callout on the plan. Silent stretching of typicals is a common source of detailing errors.
What belongs on the connection drawing
- Members, plates, bolts, welds and hole layout, dimensioned
- Material grades for plates and welds as specified
- Surface treatment conflicts (no-paint zones, galvanizing notes)
- Erection sequence notes only when they affect the connection (for example, a field splice that must close after a rafter is landed)
- A reference back to the framing plan mark
A practical workflow
- Identify who designs the connection and which standard or schedule applies.
- Plot workpoints and member setting-out from the model or design drawing.
- Choose or apply the typical; mark exceptions on the plan.
- Fit bolts and welds to the remaining section after copes.
- Check wrench and weld access, including adjacent members.
- Transfer the same information to piece drawings and the bolt list.
Engineering tips
- If two typicals differ only by bolt rows, make a schedule instead of twelve near-identical details.
- Show a wrench clearance envelope on congested details once; it prevents a dozen RFIs.
- Do not dimension the same hole from two conflicting origins.
Common mistakes
Scaling a connection from a screenshot
A PDF typical from another job may use a different bolt grade, hole type or cope rule. Re-read the current specification.
Ignoring packing plates and fills
Flange-width mismatches need fills. Leaving them off shortens bolts and creates gaps.
Putting design calculations on the shop detail
The fitter does not need your load path essay. Keep calculations in the design file; keep the detail manufacturable.
Checklist
- Workpoints shown where eccentricity matters
- Bolt grade, hole type and shop/field complete
- Weld symbols match the specification
- Copes checked against remaining bolt rows
- Typical range stated
- Exceptions marked on plans
- Bolt lengths plausible for the grip
- Finish notes include field-weld zones
Frequently asked questions
Can I copy connection details from a previous project?
Only as a starting template, and only after checking the current specification, sections and design responsibility. Geometry rarely copies cleanly.
Do I need to show every bolt on the GA?
No. GAs should point to typicals. Piece drawings and connection details carry the bolt layout.
What if the connection will not fit?
Stop. Do not thin a plate or drop a bolt row to make CAD close. That is a design change and needs the assigned designer.
How does this apply to PEB frames?
PEB connections are often manufacturer-standard (end plates, clips, flange braces). You still need workpoints, bolt tables and exception details at framed openings and crane brackets.
Where this leaves the work
Connection detailing rewards slow geometry and fast typicals. Get the workpoint and remaining section right, then repeat the approved typical without improvising.
When the set is ready for issue, run the detailing checklist with extra attention to hole groups and weld access.
This article provides general educational information. Project-specific structural design, calculations and drawings should be reviewed by appropriately qualified engineering professionals and checked against applicable project requirements and standards. StruTools does not replace engineering judgement or professional design review.