Design Timber Brackets and Hold-Downs to Eurocode 5

This tool combines the rigour of EN 1995-1-1 with the specific performance data of supplier ETAs. It includes:

• Capacity Verification (Rd): Automatically pulls characteristic strength values (Rk) from the relevant ETA and applies Eurocode 5 safety factors.
• Dynamic Visualization: A built-in 2D visual engine displays your set geometry with real-time force directions and intensities, ensuring you understand exactly how the connector is loaded.
• Smart Filtering: Filter the library by load type (e.g., “High Uplift”) to find the optimal product for your specific node.
• Nailing Patterns: Verifies the required fastener quantities (Anker nails / screws) for both the timber and the support, preventing common specification errors.
• Mixed Substrates: Supports Timber-to-Timber and Timber-to-Concrete connections.

Steel brackets are widely used in timber construction to transfer forces between structural members such as beams, columns, and supporting elements. These connectors provide reliable load transfer while simplifying installation and improving structural robustness.

SPEC Toolbox includes a dedicated Bracket Design module that allows engineers to evaluate the performance of timber connections using manufacturer-defined steel brackets. The calculator integrates real bracket geometries and fastening patterns from leading connector manufacturers, including Pitzl, Eurotec, Rothoblaas, Sihga, and Simpson Strong-Tie. Each connector is evaluated using supplier-defined geometry, hole layouts, and recommended fastener patterns.

For the European region, the calculator supports EN 1995-1-1:2004 (Eurocode 5), which defines the design rules for timber connections, including fastener resistance, spacing requirements, and timber failure verification.

To support intuitive connection configuration, the calculator provides interactive visualizations of the selected bracket geometry. Users can switch between: 3D Imagery (realistic representation of the selected bracket), 2D View (simplified representation showing dimensions and load directions), 3D Model View (interactive model that can be rotated and inspected).

Users can define: Connector supplier, Bracket category, Bracket type. Supported bracket categories: Angle brackets, Shear plates, Tension straps, Hold-down connectors. Each bracket type includes predefined geometry and hole layouts according to manufacturer specifications.

The calculator automatically applies supplier-defined fastener patterns, ensuring the connection configuration matches the manufacturer’s tested design. Patterns include: fastener diameter and type, number of fasteners, fastener spacing, fastener positioning relative to the bracket geometry.

Engineers define characteristic timber density (ρk), used to determine embedment strength of the timber and resistance of fasteners installed in the member.

The calculator allows engineers to apply all force components that the selected connector is designed to transfer, depending on bracket type and manufacturer-defined configuration: Tension forces, Shear forces, Lateral forces, Uplift forces, Multi-directional load components. Available load inputs automatically adapt to the selected bracket configuration. Applied forces are visualized in the connector model.

Bracket connections are evaluated according to EN 1995-1-1 (Eurocode 5). Design procedure considers: timber embedment strength, fastener resistance in timber, load direction relative to the grain, service class conditions, load duration factors, material safety factors. Engineers can define: service class, load duration, material safety factors, pre-drilling conditions.

Verification focuses on the timber side of the connection, evaluating interaction between the timber member and installed fasteners.

• Hold-down Design: evaluated based on fastener resistance and timber embedment strength — verifies safe transfer of uplift or tension forces into the timber member.
• Combined Force Check: evaluates interaction between multiple simultaneous forces, verifying combined loading doesn’t exceed capacity of the timber-fastener system.
• Hold-down Stiffness: provides connection stiffness value, representing deformation behavior under load — usable in structural modelling or global structural analysis.