Free Tool · CIDECT DG1 / EN 1993-1-8 §7

Hollow Section Joint Calculator

Calculate the resistance of RHS, SHS, and CHS joints per CIDECT Design Guide 1 and EN 1993-1-8 §7. Supports T, Y, K-gap, K-overlap, X, DK, and DY connections. Computes chord face plastification, punching shear, and brace efficiency ratios with pass/fail status.

CHORD b × h × t Brace 1 θ=45° Brace 2 θ=135° g N₁ N₂ L_chord Chord Brace K-gap
Joint Parameters
Braces
# Type b (mm) h (mm) t (mm) θ (°) NE,d (kN) ME,d
Joint Resistance Results
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η_max (max brace efficiency ratio)
AWAITING INPUT
Joint classification: effective — brace forces transferable via chord face
Chord —
Npl,Rd (chord) —
Connection —
Brace Efficiency Summary
Brace Axial η Chord-face η Punching η Chord-shear η
Enter parameters and calculate
Max η = N_Ed / N_Rd —
Enter parameters and calculate to see the derivation.
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FAQ

What sections does this calculator support?
RHS (Rectangular Hollow Sections), SHS (Square Hollow Sections), and CHS (Circular Hollow Sections). Both chord and braces can be any of these types.
What does chord face plastification check?
CIDECT Eq. 4.1 / EN 1993-1-8 Eq. 7.3 checks whether the chord face can transfer the brace axial force without yielding. The ratio must be ≤ 1.0. It uses an effective breadth beff based on the brace-to-chord width ratio.
When does K-gap geometry control the design?
For K-gap joints, the gap must be large enough to avoid chord web shear failure. CIDECT requires g ≥ t_brace + t_chord as a minimum. If the gap is too small the joint cannot be treated as a K-gap; overlapping K joints (K-overlap) must be used instead.
What is the punching shear check?
CIDECT Eq. 7.3 / EN 1993-1-8 §7.2.3 evaluates whether the chord wall can resist the shear flow induced by the brace around its perimeter. For RHS braces the perimeter is (b_brace + h_brace); for CHS braces it uses the perimeter formula.
Which national annexes are supported?
EN 1993-1-8 §7 applies universally. The default γM0 = 1.0 and γM2 = 1.25 are the recommended EN values, consistent with NL (NEN-EN), DE (DIN EN), and BE annexes.