Safety factors in EN 1992-4 ensure adequate reliability by accounting for uncertainties in material strength, loading, and calculation models. This page explains the factors used in anchor channel design.
Limit State Design Framework
EN 1992-4 follows the Eurocode reliability framework:
Design resistance = Characteristic resistance / Partial factor
Rd = Rk / γM
- Rk = Characteristic (5% fractile) resistance
- γM = Partial safety factor for materials
- Rd = Design resistance
Partial Factors for Resistance (γM)
Steel Failure Modes
| Mode | Symbol | Recommended Value | Notes |
|---|
| Tension (yielding) | γMs | 1.0 | When fyk used |
| Tension (ultimate) | γMs | 1.2 | When fuk used |
| Shear | γMs | 1.0 | Standard value |
| Combined | γMs | 1.2 | Conservative |
Product ETAs may specify different γMs values. Clariti uses
product-specific factors where provided in the ETA.
Concrete Failure Modes
| Mode | Symbol | Recommended Value | Notes |
|---|
| Concrete cone (tension) | γMc | 1.5 | Standard value |
| Concrete edge (shear) | γMc | 1.5 | Standard value |
| Concrete pryout | γMc | 1.5 | Standard value |
Pullout and Splitting
| Mode | Symbol | Recommended Value | Notes |
|---|
| Pullout | γMp | 1.5 | May vary by product |
| Splitting | γMsp | 1.5 | Standard value |
Why Different Factors?
Partial factors reflect uncertainty and consequences:
Steel Factors (Lower)
- Material properties well-controlled
- Manufacturing tolerances tight
- Failure mode typically ductile
- Good correlation between test and theory
Concrete Factors (Higher)
- Greater variability in concrete strength
- Sensitivity to installation quality
- Brittle failure modes
- Complex interaction with surrounding concrete
Characteristic Values
Characteristic resistance (Rk) represents the 5% fractile:
Rk = mean resistance - 1.64 × standard deviation
Determination Methods
| Source | How Rk is Determined |
|---|
| Testing | Statistical evaluation of test results |
| Calculation | EN 1992-4 equations with characteristic inputs |
| ETA data | Product-specific values from approval testing |
Load Factors (γF)
Load factors (from EN 1990) increase design loads:
| Action Type | Symbol | Typical Value |
|---|
| Permanent (unfavorable) | γG | 1.35 |
| Variable (unfavorable) | γQ | 1.5 |
| Permanent (favorable) | γG | 1.0 |
Clariti expects factored (design) loads as input. Apply load factors
before entering NEd and VEd.
Combination Factors (ψ)
For multiple variable actions:
| Factor | Symbol | Purpose |
|---|
| ψ0 | Combination | Unlikely all actions at max simultaneously |
| ψ1 | Frequent | Typical service conditions |
| ψ2 | Quasi-permanent | Long-term average |
Safety Factor Summary Table
Complete reference for standard values:
| Failure Mode | γM | Applies To |
|---|
| Steel tension | 1.2 | NRk,s |
| Steel shear | 1.0 | VRk,s |
| Concrete cone | 1.5 | NRk,c |
| Pullout | 1.5 | NRk,p |
| Splitting | 1.5 | NRk,sp |
| Concrete edge | 1.5 | VRk,c |
| Concrete pryout | 1.5 | VRk,cp |
National Annex Variations
National Annexes may modify recommended values. Examples:
| Country | Modification |
|---|
| Germany | Additional requirements for certain applications |
| UK | Generally follows recommended values |
| France | Some variations in combination factors |
Check your project’s jurisdiction for applicable National Annex.
Clariti defaults to EN 1992-4 recommended values.
Reliability Index
The target reliability index for ULS is typically:
| Consequence Class | β (50-year reference) |
|---|
| CC1 (Low) | 3.3 |
| CC2 (Medium) | 3.8 |
| CC3 (High) | 4.3 |
In Clariti
Clariti handles safety factors automatically:
- Product factors — Uses ETA-specific γM where provided
- Standard factors — Falls back to EN 1992-4 recommended values
- Transparency — Shows all factors in expanded calculations
- Override option — Advanced users can adjust factors if justified
All calculations display which factors were applied and their values, ensuring full traceability. 
