> ## 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.

# Calculations Overview

> How Clariti performs EN 1992-4 verification for anchor channels

This section explains how Clariti calculates anchor channel capacity according to EN 1992-4. Understanding the methodology helps you interpret results and make informed design decisions.

## Supported Products

Clariti supports the following cast-in anchor channel systems:

| Channel Family | Description         |
| -------------- | ------------------- |
| **CPRO38**     | Light-duty channel  |
| **CPRO50**     | Medium-duty channel |
| **CPRO52**     | Heavy-duty channel  |

All calculations use certified values from **ETA-25/0222**.

## Design Philosophy

Clariti follows the limit state design approach of EN 1992-4:

```
NRd ≥ NEd
```

Where:

* NEd = Factored design load (input by you)
* NRd = Design resistance (calculated by Clariti)

The utilization ratio is:

```
β = NEd / NRd × 100%
```

A utilization ≤ 100% means the design is adequate for that failure mode.

## Calculation Flow

For each connection, Clariti performs these steps:

1. **Validate inputs** — Check bolt positions against constraints and verify channel/bolt compatibility
2. **Calculate influence length** — Determine which anchors are affected by each load
3. **Distribute forces to anchors** — Calculate how loads transfer to individual anchors
4. **Find worst-case loading** — Identify the critical bolt position that maximises anchor forces
5. **Calculate resistances** — Determine characteristic resistances (NRk, VRk) for each failure mode
6. **Apply safety factors** — Convert to design resistances (NRd = NRk / γM)
7. **Calculate utilization** — Compare demand to capacity (β = NEd / NRd)
8. **Check interaction** — For combined loading, verify interaction equation
9. **Report results** — Identify governing failure mode (highest utilization)

## Failure Modes

Anchor channels can fail in multiple ways. Clariti checks all applicable failure modes per EN 1992-4 Table 7.4 and reports the governing one (highest utilization).

### Tension Failure Modes

Per EN 1992-4:2018, anchor channels under tension must be verified against both steel and concrete failure modes.

#### Steel Failure Modes (Tension)

| Mode                          | Description                                | What It Checks                  |
| ----------------------------- | ------------------------------------------ | ------------------------------- |
| **Anchor in tension**         | Fracture of anchor shaft                   | Anchor steel tensile capacity   |
| **Anchor channel connection** | Failure of weld between anchor and channel | Connection strength             |
| **Channel lips**              | Local failure of channel lips              | Lip bending capacity            |
| **Channel bolt**              | Fracture of the T-bolt                     | Bolt tensile capacity           |
| **Channel in bending**        | Flexural failure of channel                | Channel bending moment capacity |

#### Concrete Failure Modes (Tension)

| Mode              | Description                                  | When Critical              |
| ----------------- | -------------------------------------------- | -------------------------- |
| **Concrete cone** | Breakout of concrete cone around anchor      | Most common governing mode |
| **Pullout**       | Anchor pulls out without full cone formation | Related to bearing area    |
| **Splitting**     | Concrete splits due to wedging action        | Thin members, close edges  |
| **Blowout**       | Side breakout near edges                     | Anchors close to edges     |

### Shear Failure Modes

Per EN 1992-4:2018, anchor channels under shear must be verified against both steel and concrete failure modes.

#### Steel Failure Modes (Shear)

| Mode                          | Description                    | What It Checks            |
| ----------------------------- | ------------------------------ | ------------------------- |
| **Anchor in shear**           | Shear fracture of anchor       | Anchor shear capacity     |
| **Anchor channel connection** | Failure of connection in shear | Connection shear strength |
| **Channel bolt**              | Shear failure of T-bolt        | Bolt shear capacity       |

#### Concrete Failure Modes (Shear)

| Mode              | Description                | When Critical             |
| ----------------- | -------------------------- | ------------------------- |
| **Concrete edge** | Breakout toward free edge  | Loads acting toward edges |
| **Pryout**        | Back-side concrete failure | Short, stiff anchors      |

### Combined Loading

When both tension and shear act simultaneously, Clariti checks interaction using EN 1992-4 equations. The combined utilization must also be ≤ 100%.

## Partial Safety Factors

Material partial factors from ETA-25/0222:

| Failure Mode    | γM   | Notes    |
| --------------- | ---- | -------- |
| Steel — anchor  | 1.85 | From ETA |
| Steel — channel | 1.8  | From ETA |
| Steel — bolt    | 1.87 | From ETA |
| Concrete cone   | 1.5  | Standard |
| Pullout         | 1.5  | Standard |
| Splitting       | 1.5  | Standard |

<Note>
  Clariti uses product-specific γM values from the ETA where available, which may differ from generic EN 1992-4 values.
</Note>

## Transparency

Every calculation in Clariti can be expanded to show:

1. **Reference** — EN 1992-4 clause number
2. **Equation** — The formula being applied
3. **Inputs** — All values used with sources
4. **Factors** — Each ψ and γ factor with justification
5. **Result** — Step-by-step evaluation

This transparency allows you to:

* Verify calculations manually
* Understand why capacity is limited
* Explain results to checkers and approvers
* Learn the EN 1992-4 methodology

## Further Reading

<CardGroup cols={2}>
  <Card title="Input Constraints" icon="file">
    [Valid ranges for bolt positions and loads →](/calculations/input-constraints)
  </Card>

  <Card title="Tension Verification" icon="file">
    [Detailed tension failure mode calculations →](/calculations/tension-verification)
  </Card>

  <Card title="Shear Verification" icon="file">
    [Detailed shear failure mode calculations →](/calculations/shear-verification)
  </Card>

  <Card title="Combined Loading" icon="file">
    [Interaction checks for combined forces →](/calculations/combined-loading)
  </Card>
</CardGroup>