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How to use the eaves haunch calculator

The portal frame eaves connection: what each input means, how the haunch adds lever arm, and why the uplift case matters.

All guides Inputs Result Calc sheet Walk-through Mistakes

1. What the calculator does

The haunched end plate calculator checks the eaves connection of a portal frame: the rafter meets the column, and a haunch cut from a rafter (or built up from plates) deepens the rafter at the column so the bolts get a bigger lever arm. It uses the same component method as the end plate calculator, with the extra checks the haunch brings: the haunch flange in compression, the welds and the deeper bolt group.

The code route is the EN 1993-1-8 component method (clause 6.2) with the STATIX eaves-haunch check, as the page badge says, with published-example checks.

Eaves haunch calculator header with the PASS badge — The header: PASS 53 %, governed by the beam flange weld.

2. The inputs, group by group

Input	What it means	Typical value
Rafter and column	The rafter and column sections from the tables, and the steel grade.	457×191×67 UB rafter, 305×305×137 UC column, S355
Haunch	Depth below the rafter and length; “Haunch details” sets the flange, rafter cutting or built-up plates, and the compression stress.	300 deep, 500 long, rafter cutting
End plate	Extended or flush, width, depth (0 = the minimum) and thickness.	extended, 180 wide, 20 thick
Bolts	Size, grade, tension rows, row pitch and gauge.	M20 10.9, 4 tension rows, pitch 80, gauge 100
Actions (ULS)	Factored moment (+ gravity, − uplift), shear and axial force.	M 220 kNm, V 120 kN

Eaves haunch inputs: rafter, column, haunch, end plate, bolts and actions — The inputs. The sign of the moment matters: positive for gravity, negative for wind uplift.

3. How to read the result

The drawings show the connection to scale: the column, the rafter with the haunch under it, the end plate and the bolt rows, with M_j,Rd in the header.

Eaves connection elevation and view on the plate — Eaves connection: haunch 300 deep and 500 long, end plate 180 × 820 × 20, 6 rows of M20 10.9, M_j,Rd 587.5 kNm.

The joint resistance card gives the moment resistance, the connection depth (rafter plus haunch), the shear resistance, the compression at the haunch flange (here limited by the column web in compression), the web panel shear, the top-row tension, the critical row and the governing component.

Joint resistance card for the eaves haunch — Joint resistance: M_j,Rd 587.5 kNm, depth 753 mm (453 + 300), V_j,Rd 470 kN, F_c,Rd 939 kN (column web in compression); governing beam flange weld at 53 %.

The badge names the governing component; here the beam flange weld (8 mm legs) at 53 %. The “vs un-haunched” row shows a dash: the page says this comparison is not computed by the shared engine. Anything the engine could not run shows as NOT CHECKED.

Design checks summary for the eaves haunch — Design checks: EN 1993-1-8 · 66 pass.

4. Calc sheet and take-off

The result (pass / fail and utilisation) stays free for everyone. Every check with its clause, the calc sheet and the bending schedule are open to signed-in users. Sign in free: 3 designs a month (one calculator, open for 24 hours). Unlimited with a calculator pack.

The detail drawing sheet (PDF / DXF) is part of the paid plan. The connection take-off collects every connection of this type in the project, with the plate, bolts, welds and steel mass.

Connection take-off of all haunched eaves connections — The take-off: end plate, haunch cutting, bolts and welds, 19.6 kg for one connection.

5. A 2-minute walk-through

Open the calculator: a 457 UB rafter on a 305 UC column, 300 mm haunch, 4 tension rows of M20 10.9, M 220 kNm.
Read the badge: PASS 53 %, beam flange weld.
Enter an uplift case: M −150 kNm. The bottom of the haunch is now in tension; see which component governs.
Reduce the haunch depth to 200 mm and watch M_j,Rd fall.
Drop to 3 tension rows and see what governs.

6. Common mistakes

Only the gravity case. Wind uplift reverses the moment; check it with a negative M.
The column web forgotten. The compression from the haunch flange goes into the column web; a stiffener may be needed.
A short haunch. The haunch must be long enough for the rafter to work beyond it; the rafter design checks the end of the haunch.
Moments from an analysis without the haunch. The haunch stiffens the eaves; model it in the frame.

7. Where it fits

The eaves moment and shear come from the portal frame analysis, for every combination: gravity, wind with internal pressure, and wind uplift. The column and the rafter are checked as members in the steel member calculator; the rafter check includes the section at the end of the haunch, where the moment is still large but the depth is back to the plain rafter. The apex connection is in its own calculator.

8. Learn more

Try it nowThe calculator opens with the walk-through inputs above. The result is free; sign in for the checks, calc sheet and schedule.
Open the eaves haunch calculator

A guide to using the calculator, not a design. Check every value against the current code and your own project, and have the design checked and signed by a registered professional engineer.

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