> ## Documentation Index
> Fetch the complete documentation index at: https://docs.clariti.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Load Combinations

> Understanding load combinations for anchor channel design per Eurocode

Load combinations determine the design loads (N<sub>Ed</sub>, V<sub>Ed</sub>) 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<sub>G</sub> = 1.35 (unfavorable) or 1.0 (favorable)

### Live Load (Q)

Variable loads from occupancy:

| Category     | Example       | ψ<sub>0</sub> | ψ<sub>1</sub> | ψ<sub>2</sub> |
| ------------ | ------------- | ------------- | ------------- | ------------- |
| 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 |
| ------------- | ----- |
| ψ<sub>0</sub> | 0.6   |
| ψ<sub>1</sub> | 0.2   |
| ψ<sub>2</sub> | 0.0   |

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

### Snow Load (S)

Variable environmental load (altitude dependent):

| Altitude | ψ<sub>0</sub> | ψ<sub>1</sub> | ψ<sub>2</sub> |
| -------- | ------------- | ------------- | ------------- |
| \< 1000m | 0.5           | 0.2           | 0.0           |
| > 1000m  | 0.7           | 0.5           | 0.2           |

### Temperature (T)

Thermal actions:

| Parameter     | Value |
| ------------- | ----- |
| ψ<sub>0</sub> | 0.6   |
| ψ<sub>1</sub> | 0.5   |
| ψ<sub>2</sub> | 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.

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

## Worked Example

Facade bracket supporting a cladding panel:

### Input Loads (Characteristic)

| Action                  | Vertical (Tension) | Horizontal (Shear) |
| ----------------------- | ------------------ | ------------------ |
| Dead load G<sub>k</sub> | 8 kN               | 0 kN               |
| Wind W<sub>k</sub>      | 0 kN               | 12 kN              |
| Live Q<sub>k</sub>      | 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<sub>Ed</sub>: Tension (anchor in tension)
* Negative N<sub>Ed</sub>: Compression (toward concrete)
* V<sub>Ed</sub>: 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.

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

### 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:

1. **Single load case**: Enter N<sub>Ed</sub> and V<sub>Ed</sub> directly
2. **Multiple cases**: Define several load cases, check each

### What to Enter

| Input Field    | What to Enter                     |
| -------------- | --------------------------------- |
| N<sub>Ed</sub> | Factored design tension (kN)      |
| V<sub>Ed</sub> | Factored design shear (kN)        |
| Direction      | Shear direction relative to edges |

### Multiple Load Cases

For comprehensive verification:

1. Create load cases for each combination
2. Clariti checks all modes for each case
3. Results show which case governs
4. Export includes all cases

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