A gusset plate gathering several truss members at one panel point needs each member's bolt group checked independently, plus the plate itself checked in both net-section tension and block tearing — and a narrow effective width combined with a modest edge distance is a common way for the plate, not any individual bolt group, to end up the weak link.

Every check above runs automatically inside the Structyze Truss Gusset Plate Connection module — this particular module is part of the full desktop catalogue rather than the free browser trial, since the trial only carries a curated flagship set. You can still try the free trial modules right now to see the same calculation style in action on RCC Beam, Column, Slab and a handful of others.

The Example We'll Use

• Bolted connection, 3 members (chord + diagonal) at the joint
• Gusset 10 mm, f_y = 235 MPa, f_u = 360 MPa
• Bolt M20, Grade 4.6; edge distance 35 mm, pitch 60 mm
• Member forces: top chord +150 kN, bottom chord −120 kN, diagonal +80 kN (4 bolts each)

Working Through It

Each member's own bolt group checks independently against the same bearing/shear logic as a simple lap joint: governing capacity per bolt 47.05 kN, group capacity 188.2 kN — the top chord (150 kN) runs tightest at utilisation 0.797, well ahead of the bottom chord (0.638) and diagonal (0.425).

The governing member for the plate itself is the top chord, since it carries the largest force and is tensile. Net-section tension uses an effective width of just twice the edge distance (2×35 = 70 mm); after deducting the 21 mm bolt hole, the net area is only 490 mm², giving a rupture capacity N_u,Rd = 0.9(490)(360)/1.25 ≈ 127.0 kN.

That 127.0 kN capacity is below the 150 kN demand — the gusset plate's own net-section rupture truly fails at utilisation 1.181, even though every bolt group and the block tearing check (utilisation 0.286) both pass with real margin.

What Governs, and Why

The gusset plate's net-section rupture is the single governing check for the whole joint, and it fails — not a modelling artifact, but a realistic outcome for a single-bolt-line connection at a fairly tight edge distance. The narrow effective width (twice the edge distance) leaves too little net area once the bolt hole is deducted, at EC3's own γ_M2 = 1.25 tension-fracture factor.

Where Structyze Takes Over

Every check above runs automatically inside the Structyze Truss Gusset Plate Connection module — this particular module is part of the full desktop catalogue rather than the free browser trial, since the trial only carries a curated flagship set. You can still try the free trial modules right now to see the same calculation style in action on RCC Beam, Column, Slab and a handful of others.

For Truss Gusset Plate Connection and the rest of the full catalogue — 80+ components across RCC, Steel, Composite, Timber, Masonry and more, across 20+ design codes — buy the full Structyze desktop app or see everything it does on the Software page.

Quick FAQ

How would you actually fix this connection?

Increasing the edge distance (which widens the effective width beyond 70 mm), increasing the gusset thickness, or moving to two bolt rows to spread the tension path would each restore margin — but any change needs re-verifying against every other check, since a thicker or wider plate also changes the block-tearing net areas.

Why check net-section tension only for the governing member?

The highest-force tensile member at a joint is, by definition, the one most likely to govern the plate's own tension check — a compression member doesn't develop the same net-section rupture risk, so checking the governing tensile member alone is the standard simplified approach for a panel-point connection.

Final Thoughts

A gusset plate's net-section tension check genuinely failing, while every bolt group passes comfortably, is just the kind of result that's easy to miss if you only check the bolts by hand and assume the plate is fine.