Staple Capacity to EC5 §8.4
Project
Ref
Engineer
Date
Service classMembers
Staple
d = √(b₁·b₂) = 1.40 mm (derived, §8.4(2))
Headside
Pointside (timber)
Timber-timber, single shear (staple)
Johansen Yield Modes - per leg
| Mode | EC5 ref | Fv,Rk per leg (N) |
|---|---|---|
| a | EC5 Eq. 8.6 (a) | 907.8 |
| b | EC5 Eq. 8.6 (b) | 907.8 |
| c | EC5 Eq. 8.6 (c) | 376.0 |
| d | EC5 Eq. 8.6 (d) | 334.8 |
| e | EC5 Eq. 8.6 (e) | 334.8 |
| f ◄ | EC5 Eq. 8.6 (f) | 198.7 |
Modes are the capacity of ONE LEG. EC5 §8.4 provides no withdrawal model for staples, so Fax,Rk = 0 and the §8.2.2(2) rope contribution is zero - the Johansen value is the characteristic value.
Geometry - EC5 §8.4(3)
| Crown width b ≥ 6d (8.4 mm) | 11.0 mm ✓ OK |
| Pointside penetration t2 ≥ 14d (19.6 mm) | 25.0 mm ✓ OK |
| Leg length ℓ → embedded penetration t2 | 50 → 25.0 mm |
EC5 Minimum Spacings - Table 8.3 (staples)
Timber (headside) - α = 0°
| Spacing parallel to grain (a1) - θ ≥ 30° branch | 21.0 mm |
| Spacing perpendicular to grain (a2) | 21.0 mm |
| Loaded end distance (a3,t) | 28.0 mm |
| Unloaded end distance (a3,c) | 21.0 mm |
| Loaded edge distance (a4,t) | 21.0 mm |
| Unloaded edge distance (a4,c) | 14.0 mm |
Timber (pointside) - α = 0°
| Spacing parallel to grain (a1) - θ ≥ 30° branch | 21.0 mm |
| Spacing perpendicular to grain (a2) | 21.0 mm |
| Loaded end distance (a3,t) | 28.0 mm |
| Unloaded end distance (a3,c) | 21.0 mm |
| Loaded edge distance (a4,t) | 21.0 mm |
| Unloaded edge distance (a4,c) | 14.0 mm |
Lateral Design Capacity
| Arrangement | Timber-timber, single shear (staple) |
| Leg diameter d = √(b₁·b₂) (§8.4(2), derived) | 1.40 mm |
| My,Rk (Eq 8.29, 150·d³ - A2:2014) | 411.1 N·mm |
| Governing mode | f |
| Fv,Rk per leg | 198.7 N |
| × 2 (§8.4(5) - two legs, θ > 30°) | × 2 |
| Fv,Rk per staple | 397.4 N |
| γM,connection | 1.30 |
Fv,Rd = kmod · Fv,Rk,staple / γM - per EC5 Table 3.1 load-duration class:
| Load duration | kmod | Rd (N) | kN |
|---|---|---|---|
| Permanent | 0.6000 | 183 | 0.18 |
| Long-term | 0.7000 | 214 | 0.21 |
| Medium-term | 0.8000 | 245 | 0.24 |
| Short-term | 0.9000 | 275 | 0.28 |
| Instantaneous | 1.1000 | 336 | 0.34 |
Assumptions & advisory notes
- Geometry: ℓ = 50 mm, headside 25 mm, pointside 47 mm → embedded penetration t2 = 25.0 mm (= pointside bearing length in the Johansen modes, EC5 Fig. 8.4).
- Leg diameter d = √(b1·b2) = √(1.53 × 1.28) = 1.399 mm (EC5 §8.4(2)) - derived, not entered. All d-dependent limits (6d, 14d, Eq 8.18) and the Johansen modes use this value.
- Nail rules per §8.4(1) (§8.3 applies except 8.3.1.1(4), 8.3.1.1(6) and 8.3.1.2(7)): embedment Eq 8.15 (not predrilled, angle-independent per §8.3.1.1(3)). Johansen modes run on d, PER LEG.
- My,Rk = 411.1 N·mm - Eq 8.29 (150·d³, EN 1995-1-1:2004+A2:2014 §8.4(6), valid for wire with fu ≥ 800 N/mm²). No fu input: the 800 N/mm² is baked into the 150 coefficient.
- Crown-to-grain angle θ = 90° > 30° - capacity per staple per shear plane = two nails of the staple diameter (§8.4(5)): factor 2 on the per-leg capacity. Per-leg Fv,Rk = 198.7 N → per-staple Fv,Rk = 397.4 N.
- Minimum spacings are EC5 Table 8.3 (staples), not Table 8.2 (nails); the a1 row takes the θ ≥ 30° branch at θ = 90°.
Fv,Rk (per staple)0.40 kN
Permanent0.18 kN
Long-term0.21 kN
Medium-term0.24 kN
Short-term0.28 kN
Instantaneous0.34 kN