Load Combinations

Load combinations determine the design loads (N_Ed, V_Ed) that Clariti uses for verification. This page explains how loads are combined according to Eurocode principles.

Load Combination Framework

EN 1990 defines how actions (loads) are combined for structural design. These combinations produce the design loads input to Clariti.

Ultimate Limit State (ULS)

The primary design verification:

Ed = γG·Gk + γQ·Qk,1 + Σ(γQ·ψ0,i·Qk,i)

Where:
  Gk = characteristic permanent action
  Qk,1 = dominant variable action
  Qk,i = other variable actions
  γG = partial factor for permanent (1.35)
  γQ = partial factor for variable (1.5)
  ψ0 = combination factor

Serviceability Limit State (SLS)

For deflection and durability checks:

Characteristic:    Ed = Gk + Qk,1 + Σ(ψ0,i·Qk,i)
Frequent:         Ed = Gk + ψ1,1·Qk,1 + Σ(ψ2,i·Qk,i)
Quasi-permanent:  Ed = Gk + Σ(ψ2,i·Qk,i)

Common Load Cases

Dead Load (G)

Permanent, constant loads:

Self-weight of structure
Fixed equipment
Permanent fixtures

Factor: γ_G = 1.35 (unfavorable) or 1.0 (favorable)

Live Load (Q)

Variable loads from occupancy:

Category	Example	ψ₀	ψ₁	ψ₂
A (Domestic)	Residential	0.7	0.5	0.3
B (Office)	Commercial	0.7	0.5	0.3
C (Assembly)	Public spaces	0.7	0.7	0.6
D (Retail)	Shops	0.7	0.7	0.6

Wind Load (W)

Variable environmental load:

Parameter	Value
ψ₀	0.6
ψ₁	0.2
ψ₂	0.0

Wind typically produces horizontal (shear) loads on anchor connections.

Snow Load (S)

Variable environmental load (altitude dependent):

Altitude	ψ₀	ψ₁	ψ₂
< 1000m	0.5	0.2	0.0
> 1000m	0.7	0.5	0.2

Temperature (T)

Thermal actions:

Parameter	Value
ψ₀	0.6
ψ₁	0.5
ψ₂	0.0

Temperature changes can induce restraint forces in fixed connections.

ULS Combination Equations

Equation 6.10 (General)

Ed = 1.35·Gk + 1.5·Qk,1 + 1.5·Σ(ψ0,i·Qk,i)

Single equation covering all permanent and variable actions.

Equations 6.10a and 6.10b (Alternative)

Some National Annexes use:

6.10a: Ed = 1.35·Gk + 1.5·ψ0·Qk,1 + 1.5·Σ(ψ0,i·Qk,i)
6.10b: Ed = ξ·1.35·Gk + 1.5·Qk,1 + 1.5·Σ(ψ0,i·Qk,i)

Where ξ = 0.85 (typical)

Use the more critical result.

Check your National Annex for which approach applies. Clariti accepts factored design loads regardless of the combination method used.

Worked Example

Facade bracket supporting a cladding panel:

Input Loads (Characteristic)

Action	Vertical (Tension)	Horizontal (Shear)
Dead load G_k	8 kN	0 kN
Wind W_k	0 kN	12 kN
Live Q_k	2 kN	0 kN

Combination 1: Dead + Wind (Primary)

NEd = 1.35 × 8 + 1.5 × 0.7 × 2 = 12.9 kN
VEd = 1.5 × 12 = 18.0 kN

Combination 2: Dead + Live (Primary)

NEd = 1.35 × 8 + 1.5 × 2 = 13.8 kN
VEd = 1.5 × 0.6 × 12 = 10.8 kN

Design Loads

Both combinations should be checked. The governing combination may differ depending on which failure mode controls.

Load Direction Considerations

Tension vs. Compression

Tension (away from concrete): Engages anchor capacity
Compression (into concrete): May provide friction benefit

Shear Direction

Toward edge: Concrete edge failure likely governs
Away from edge: Pryout or steel may govern
Parallel to edge: Direction affects capacity

Sign Convention

In Clariti:

Positive N_Ed: Tension (anchor in tension)
Negative N_Ed: Compression (toward concrete)
V_Ed: Specify direction relative to edges

Special Situations

Seismic Loading

Seismic combinations per EN 1998:

Ed = Gk + AEd + ψ2·Qk

Where AEd = seismic action

Partial factors may be modified for seismic design situations.

Seismic design requires additional considerations per EN 1992-4 Annex C. Products must be qualified for seismic applications.

Accidental Loading

For accidental design situations (impact, explosion):

Ed = Gk + Ad + ψ1·Qk,1 + Σ(ψ2,i·Qk,i)

Where Ad = accidental action

Partial factors γ = 1.0 for accidental combinations.

Fatigue Loading

For cyclic loading:

Reduced partial factors may apply
Fatigue verification per EN 1992-4 Section 4.4
Product-specific fatigue data required

In Clariti

Load Input

Clariti expects factored design loads:

Single load case: Enter N_Ed and V_Ed directly
Multiple cases: Define several load cases, check each

What to Enter

Input Field	What to Enter
N_Ed	Factored design tension (kN)
V_Ed	Factored design shear (kN)
Direction	Shear direction relative to edges

Multiple Load Cases

For comprehensive verification:

Create load cases for each combination
Clariti checks all modes for each case
Results show which case governs
Export includes all cases

If unsure which combination governs, enter multiple cases. Clariti will identify the critical one for each failure mode.

Getting Started

How Calculations Work

EN 1992-4 Reference

User Guides

Load Combination Framework

Ultimate Limit State (ULS)

Serviceability Limit State (SLS)

Common Load Cases

Dead Load (G)

Live Load (Q)

Wind Load (W)

Snow Load (S)

Temperature (T)

ULS Combination Equations

Equation 6.10 (General)

Equations 6.10a and 6.10b (Alternative)

Worked Example

Input Loads (Characteristic)

Combination 1: Dead + Wind (Primary)

Combination 2: Dead + Live (Primary)

Design Loads

Load Direction Considerations

Tension vs. Compression

Shear Direction

Sign Convention

Special Situations

Seismic Loading

Accidental Loading

Fatigue Loading

In Clariti

Load Input

What to Enter

Multiple Load Cases

​Load Combination Framework

​Ultimate Limit State (ULS)

​Serviceability Limit State (SLS)

​Common Load Cases

​Dead Load (G)

​Live Load (Q)

​Wind Load (W)

​Snow Load (S)

​Temperature (T)

​ULS Combination Equations

​Equation 6.10 (General)

​Equations 6.10a and 6.10b (Alternative)

​Worked Example

​Input Loads (Characteristic)

​Combination 1: Dead + Wind (Primary)

​Combination 2: Dead + Live (Primary)

​Design Loads

​Load Direction Considerations

​Tension vs. Compression

​Shear Direction

​Sign Convention

​Special Situations

​Seismic Loading

​Accidental Loading

​Fatigue Loading

​In Clariti

​Load Input

​What to Enter

​Multiple Load Cases

Load Combination Framework

Ultimate Limit State (ULS)

Serviceability Limit State (SLS)

Common Load Cases

Dead Load (G)

Live Load (Q)

Wind Load (W)

Snow Load (S)

Temperature (T)

ULS Combination Equations

Equation 6.10 (General)

Equations 6.10a and 6.10b (Alternative)

Worked Example

Input Loads (Characteristic)

Combination 1: Dead + Wind (Primary)

Combination 2: Dead + Live (Primary)

Design Loads

Load Direction Considerations

Tension vs. Compression

Shear Direction

Sign Convention

Special Situations

Seismic Loading

Accidental Loading

Fatigue Loading

In Clariti

Load Input

What to Enter

Multiple Load Cases