Free Tool · EN 1993-1-8 §3.5/§3.6
Bolt Capacity Calculator
Calculate bolt shear resistance Fv,Rd, tension resistance Ft,Rd, bearing resistance Fb,Rd and combined utilisation per EN 1993-1-8 Table 3.4. Live results — no sign-up needed.
Fv,Rd Shear
Ft,Rd Tension
Fb,Rd Bearing
γM2=1.25
M12–M36
4.6 · 5.6 · 8.8 · 10.9 · 12.9
NL / DE / BE
No sign-up
Results
Fv,Rd §3.6
—
Ft,Rd §3.6
—
Fb,Rd §3.5
—
Governing Rd
—
γM2
1.25
Combined check §3.6
—
Enter loads above to check utilisation.
Pro feature
Need this for every bolt in a 200-connection job?
Pro runs the full connection schedule from your PDF in 4 minutes — shear, bearing, tension, weld sizing, and fabrication drawings included.
See Pro plans →
Methodology
EN 1993-1-8 §3.5 & §3.6 Formulas
Shear resistance per bolt per shear plane:
Fv,Rd = (αv · fub · A) / γM2,
where αv = 0.6 for grades 4.6/5.6/8.8 and 0.5 for 10.9/12.9 when the shear plane is through threads.
A is the gross shank area when the shear plane passes through the unthreaded portion, otherwise the thread stress area Ath.
Tension resistance: Ft,Rd = (0.9 · fub · Ath) / γM2.
Bearing resistance:
Fb,Rd = (k₁ · αb · fu · d · t) / γM2,
where k₁ = min(2.8·e₂/d₀ − 1.7, 2.5) and αb = min(e₁/(3·d₀), fub/fu,plate, 1.0).
Combined shear + tension interaction check per §3.6:
Fv,Ed/Fv,Rd + Ft,Ed/(1.4·Ft,Rd) ≤ 1.0.
National annex γM2: EN/NL/DE/BE all use 1.25.
For preloaded bolts (EN 1993-1-8 §3.9), γM3 = 1.25 (service) / 1.1 (ULS slip) apply instead — not covered by this tool.
FAQ
Frequently Asked Questions
When should I use grade 10.9 vs 8.8 bolts?
▾
Use 8.8 when geometry allows — it's cheaper, more widely available, and easier to install. Upgrade to 10.9 when the connection is space-constrained (fewer, smaller bolts needed), when the shear demand exceeds the 8.8 capacity, or when using preloaded slip-resistant joints (HSFG). 12.9 is reserved for specialized applications; it's brittle under impact and typically not permitted in seismic zones.
What is γM2 and why is it 1.25?
▾
γM2 is the partial factor for bolt resistance (fracture in tension, shear, or bearing). It is 1.25 in the EN default and in the NL, DE, and BE national annexes. A higher value than the γM0=1.0 used for cross-sections reflects the greater uncertainty in bolt installation (torque, thread condition, clamping force). Some national annexes allow γM2=1.2 for specific preloaded bolt types.
What does "threads in shear plane" mean?
▾
If the shear plane passes through the threaded portion of the bolt shank, you must use the tensile stress area A_s (thread area) for computing shear resistance, and apply α_v = 0.5 for grade 10.9/12.9 (instead of 0.6 for the shank). This is conservative and typically applies when bolt length is not controlled precisely. The shank area is 20–35% larger — always prefer shear through the smooth shank when layout allows.
What is the combined check formula for shear + tension?
▾
EN 1993-1-8 §3.6: F_v,Ed/F_v,Rd + F_t,Ed/(1.4·F_t,Rd) ≤ 1.0. Note the factor 1.4 on the tension resistance — this is a relaxation because the shear and tension peaks don't occur simultaneously at the same location. Keep F_t,Ed ≤ F_t,Rd independently as well.
When should I use preloaded HV bolts instead of standard bolts?
▾
Use preloaded bolts (EN 14399 HV sets) when slip at serviceability limit state is unacceptable — e.g. connections subject to load reversal, fatigue, or vibration; connections required to be "slip-resistant" by the structural model; or Category C connections (bearing at ULS, no slip at SLS). Preloaded bolts are also used in seismic connections and for joints where clearance tolerances must be eliminated. For ordinary bearing-type connections under static load, standard non-preloaded bolts per EN 15048 are sufficient.
Related
More EN 1993-1-8 Tools