Design Sihga Brackets to Eurocode 5

Sihga GmbH (Ohlsdorf, Austria) manufactures fastening and connection systems for timber construction, from wood connectors to decking. Its Mass-X brackets are recognized under ETA-23/0353. SPEC Toolbox designs them to Eurocode 5 using the characteristic load-carrying capacities of the assessment.

The plates are one-piece pre-galvanized steel: S355 for the welded Pull Angle P-HB hold-downs, S250GD/Z275 for the Angle Q, Angle Z, Shear and Pull families, and S235 for the Angle Q HH and HB and the base plates. Angle bracket thickness is 2.5 to 4 mm, base plates 10 to 40 mm. Brackets are fixed to timber with ringed shank nails, screws, bolts or Idefix connectors, and to concrete or steel with bolts or metal anchors.

Hold-downs

• Pull Angle P-HB 340, 440 and 750, welded plates for uplift, each with its base plate for concrete or steel, plus the Angle Z and the Angle Q and Angle Q HB on the 230 base plate.

Angle brackets and shear angles

• Angle Q (230 x 120 mm), bare and with the Mass-X Angle decoupling, Angle Q HH for timber and Angle Q HB for concrete on the flat 230 mm profile, and Angle Z (120 x 80 mm) for CLT.

Shear plates

• Mass-X Shear (230 x 240 mm), listed as Shear HH in the assessment.

Tension straps

• Pull HH60 and HH70 for timber, Pull HB60 and HB70 for concrete.

At a glance, the Sihga Mass-X brackets support:

• Timber-to-timber, timber-to-concrete and timber-to-steel connections.
• Solid timber, glulam, glued solid timber, LVL and CLT, characteristic density 290 to 460 kg/m3.
• Tension and uplift (F1), shear (F2/F3) and lateral (F4/F5) directions, with a combined-force interaction where they act together.
• Ringed shank connector nails, self-tapping screws of 5 to 10 mm, bolts or metal anchors of 12 to 28 mm, or Idefix connectors.
• Service classes 1 and 2, and service class 3 where corrosion protection to Eurocode 5 is applied.

• Capacity built from the fastener configuration. For the Angle Z the assessment gives expressions rather than one plate value: two to four GoFix S+ screws at 45 degrees resolved into uplift, against the bolts or Idefix connectors in each flap, the lesser governing.
• Capacities keyed to the CLT grain direction. Angle Z Idefix capacities are assessed at 400 kg/m3 both parallel and perpendicular to the outer-layer grain, with linear interpolation between.
• An assessed decoupling configuration. The Angle Q is integrated bare and with the Mass-X Angle decoupling; the 6 mm interlayer case carries its own shear capacities and a 0.9 reduction on the bolt and Idefix values.
• Ductility class DCM for CLT shear walls. With 4 mm ringed shank nails or 5 mm screws, the Angle Q and Angle Z reach an assessed static ductility ratio above four in shear between CLT shear walls and timber floors.
• Slip moduli, some set by a reference slip. Fixed values are given for the Angle Q HH and HB; for the Angle Z the modulus is the characteristic capacity divided by 6 mm in F1, 2 mm in F2/F3 and 2.5 mm in F4 or F5.

The Sihga Mass-X brackets are available in the bracket module and CLT Shear Wall calculator, worked to Eurocode 5:

• hold-down (tension and uplift anchorage);
• angle bracket and shear angle (shear and combined loading);
• shear plate;
• tension strap.

Capacities are selected for the assigned strength class and density, the fastener set and the load direction, with the combined-force interaction where directions act together, and end, edge and spacing per the assessment and Eurocode 5.

Design follows Eurocode 5 (EN 1995-1-1). ETA-23/0353 gives characteristic capacities in the F1 (tension and uplift), F2/F3 (shear) and F4/F5 (lateral) directions, together with connection slip moduli. The design capacity is the lesser of the timber-connection failure (fastener embedment or withdrawal, with k_mod and the connection partial factor) and the steel-plate failure (with the steel partial factor). Characteristic capacities are stated at 350 kg/m3, or 400 kg/m3 for the assessed CLT cases, and adjusted by the density factor k_dens; lateral fastener capacities are taken for a thick steel plate. Service classes 1 and 2 apply, and service class 3 with corrosion protection to Eurocode 5. Splitting under the lifting force and the design of fixings into concrete or steel are verified per Eurocode 5.