Apex Haunch Connection Calculator — Portal Ridge

Haunched apex (ridge) moment connection for a portal frame — two rafters meet at the ridge with a bolted end-plate and an under-rafter haunch; EN 1993-1-8 §6.2 component method. The joint is symmetric about the ridge: two identical bolted end-plates (one on each rafter) bolt together, inclined at the roof pitch, with a triangular haunch cut welded under each rafter. The connection deepens (depth = rafter depth + haunch depth), tension bolt rows gain larger lever arms h_r, compression transfers through the haunch bottom flange (the centre of compression), and M_j,Rd = Σ F_tr,Rd·h_r rises versus a plain apex end-plate. With no column the row resistance is min(end-plate T-stub, bolt row 2·F_t,Rd). Enter the rafters, roof pitch, haunch, end-plate, bolt rows and M/V/N for the live apex elevation, the bolt-row tension distribution over the deeper connection, haunch-flange compression, M_j,Rd, V_j,Rd, full checks and a printable calc sheet.

Runs the validated STATIX connection engine — verified against EN 1993-1-8 T-stub & end-plate M_j,Rd worked examples and the STATIX apex-haunch check

Inputs

Connection

Name / mark

Design code

Single-code module — haunched apex (ridge) moment end-plate connection by the EN 1993-1-8 §6.2 component method. Symmetric joint, no column: row resistance = min(end-plate T-stub, bolt row 2·F_t,Rd); haunch-flange compression. γ_M0=1.0, γ_M2=1.25.

Members

Rafters UB · both sides

Roof pitch apex ∠ = 180−2·pitch

deg

Steel grade f_y

Apex haunch

Depth h_h below rafter

Length L_h

Cut from

Flange thk t_fh

End-plate

Type

Width b_p

Depth h_p

Thickness t_p

Bolts

Size

Grade

Tension rows

Row pitch p

Gauge g

Welds

Flange leg a_f

Web leg a_w

Applied actions (ULS)

Moment M apex

kNm

Shear V

Axial N

Apex elevation — ridge · two rafters · haunch

Bolt-row tension distribution over the deepened connection

Design result

—

enter loading

Moment resistance M_j,Rd	—
vs plain apex · lever gain	—
Connection depth (rafter + haunch)	—
Roof pitch / apex angle	—
Shear resistance V_j,Rd	—
Compression resist. F_c,Rd (haunch flange)	—
Top-row tension F_t1,Rd	—
Critical row / lever z₁	—
Governing component	—
Utilisation	—

End-plate detail

Design checks

Step-by-step calculation

Connection take-off — all haunched apex connections

Every haunched apex (ridge) connection in the project, aggregated into a fabrication take-off — two end-plates, two haunch cuttings, bolts and welds per element with estimated steel mass (an apex joins two rafters, so plates and haunches come in pairs). Use “Add connection” above to build the schedule, then Download PDF (print → Save as PDF). Masses are nominal for take-off only.

This isn't a toy calculator

It runs the same component-method engine as STATIX — a full structural suite whose connection module is validated against EN 1993-1-8 T-stub, end-plate M_j,Rd, column-web and haunch worked examples. The full 3D modeller with native CBFEM is coming soon. Model the whole portal frame and every eaves and apex haunch, not just one joint.

Get early access →