Use this rectangular weld group properties calculator to calculate the geometric properties of a closed rectangular fillet weld group. The calculator determines total weld length, effective throat thickness, total effective throat area, centroid position, second moment of area about the x-axis and y-axis, and polar moment of inertia.
This calculator calculates the geometric properties of a rectangular weld group made from four fillet welds forming a closed rectangle. These properties are commonly used as the starting point for weld group stress calculations involving brackets, fabricated frames, supports and welded connections.
The calculator provides:
This calculator applies to a closed four-sided rectangular weld group. It should not be used for C-shaped welds, L-shaped welds or separate parallel weld lines.
Total weld length:
Effective throat thickness:
Total effective throat area:
Centroid location:
Second moment of area about x-axis:
Second moment of area about y-axis:
Polar moment of inertia:
| Symbol | Description | Units |
|---|---|---|
| b | Rectangular weld group width | mm |
| d | Rectangular weld group depth | mm |
| h | Fillet weld size | mm |
| a | Effective throat thickness | mm |
| L | Total weld length | mm |
| A | Total effective throat area | mm² |
| x̄ | Centroid position in x-direction | mm |
| ȳ | Centroid position in y-direction | mm |
| Ixx | Second moment of area about x-axis | mm³ |
| Iyy | Second moment of area about y-axis | mm³ |
| J | Polar moment of inertia | mm³ |
Enter the weld group dimensions and click calculate.
| Result | Meaning |
|---|---|
| Total weld length | The total length of weld around the closed rectangular weld group. |
| Effective throat thickness | The theoretical effective throat thickness of the fillet weld, calculated as 0.707 times the weld size. |
| Total effective throat area | The effective weld area based on the closed rectangular weld group perimeter. |
| Centroid position | The centre of the rectangular weld group. |
| Second moment of area, Ixx | A weld group property used in bending stress calculations about the x-axis. |
| Second moment of area, Iyy | A weld group property used in bending stress calculations about the y-axis. |
| Polar moment of inertia, J | A weld group property used in torsional weld stress calculations. |
This calculator determines geometric properties for a closed rectangular fillet weld group. It does not calculate final weld stress, resultant stress, utilisation or pass/fail strength checks.
| This Calculator Includes | This Calculator Does Not Include |
|---|---|
| Total weld length | Applied force inputs such as Vx or Vy |
| Effective throat area | Applied moments or torsion inputs such as M or T |
| Centroid location | Resultant weld stress calculation |
| Ixx, Iyy and J | Pass/fail weld strength check |
| Closed rectangular weld group properties | C-shaped, L-shaped or parallel-line weld groups |
For a simple direct shear weld strength check, use the Fillet Weld Strength & Size Calculator.
This calculator is intended for a rectangular weld group made up of four fillet welds forming a closed rectangle. The resulting geometric properties are commonly used in weld group stress calculations for brackets, frames and fabricated components.
The total effective throat area is calculated from the total weld length and effective throat thickness. The centroid location, second moment of area and polar moment of inertia are then calculated using standard weld group property formulae.
To calculate the effective throat area of a simple fillet weld, use the Weld Throat Area Calculator.
To calculate weld shear stress, utilisation and required weld size for a direct shear fillet weld, use the Fillet Weld Strength & Size Calculator.
For further weld strength formulae and weld group properties, see the RoyMech reference page: Weld Strength Formulae and Weld Group Properties.
A rectangular weld group is a weld arrangement made from four welds forming a rectangular shape. It is commonly used for bracket welds, fabricated frames, machinery supports and structural welded connections.
The total weld length for a rectangular weld group is calculated as:
where b is the weld group width and d is the weld group depth.
The total effective throat area for a rectangular fillet weld group is calculated as:
where h is the fillet weld size, b is the weld group width and d is the weld group depth.
For a symmetrical rectangular weld group, the centroid is located at the centre of the rectangle:
The second moment of area about the x-axis is:
The second moment of area about the y-axis is:
For the rectangular weld group formula used in this calculator, the polar moment of inertia is:
No. This calculator calculates weld group geometric properties such as total weld length, throat area, centroid, second moment of area and polar moment of inertia. These properties can then be used in later weld stress and strength calculations.