Dowel & Bolt Connection Design

1. The Johansen Yield Theory (Automated)

Eurocode 5 requires checking multiple failure modes—from timber embedment failure to fastener yielding (plastic hinge formation).

Our calculator runs the full matrix of equations for every load case. It automatically identifies whether the failure is ductile (steel yield) or brittle (wood crushing) and applies the correct “Rope Effect” contribution ($F_{ax,Rk}/4$) where applicable.

2. Combined Actions (Shear + Axial + Moment)

Real-world connections rarely see pure shear. A truss chord connection sees shear and tension. A portal frame knee sees moment.

We use an Elastic Analysis method to distribute forces to individual fasteners based on their stiffness and distance from the center of rotation. This gives you the “True Behavior” of the group, ensuring no single bolt is overloaded.

3. Steel Plate Verification

A strong bolt is useless in a weak plate. The module integrates Eurocode 3 (Steel Design) checks for the metal components.

It verifies:

• Plate Bearing: Preventing the bolt from tearing through the steel.
• Plate Yielding: Ensuring the steel plate cross-section can handle the tension/shear forces.
• Net Section Tension: Checking failure through the bolt holes.

Load Carrying Capacity ($F_{v,Rd}$):

$$F_{v,Rd} = \min \left( \text{Johansen Yield Modes} \right) + \Delta F_{v,rope}$$

The tool automatically limits the rope effect contribution to the strict Eurocode limits (max 15% or 25% depending on the fastener type).

Group Effect ($n_{ef}$):

$$n_{ef} = n^{0.9} \sqrt[4]{a_1 / (13d)}$$

For fasteners in a row parallel to the grain, the effective number of bolts is reduced to account for uneven load distribution. The tool calculates this automatically based on your spacing ($a_1$).

Interaction Formula (Combined Loads):

For bolts subject to combined shear ($F_{v,Ed}$) and axial tension ($F_{ax,Ed}$):

$$\left(\frac{F_{v,Ed}}{F_{v,Rd}}\right)^2 + \left(\frac{F_{ax,Ed}}{F_{ax,Rd}}\right)^2 \le 1.0$$