Lifting Lug Design Calculations

Designing a lifting lug requires several key calculations to ensure its safety and effectiveness. Here are the main calculations needed for lifting lug design, along with sample calculations:

Tensile Capacity

The tensile capacity of the lug is crucial to ensure it can withstand the applied load without failure.

Sample calculation

For a lug with thickness , length , and material tensile strength of :

Tensile capacity = (tensile strength * thickness * length) / safety factor

where is the safety factor.

Bearing Capacity

Bearing capacity ensures the lug can withstand the pressure exerted by the pin without deformation.

Sample calculation

For the lug with thickness , length , pin diameter , and material yield strength of :
Bearing capacity = (yield strength * thickness * length) / (pin diameter * safety factor)

Shear Capacity

Shear capacity ensures the lug can resist the shearing forces applied during lifting.

Pin Tear-out Resistance

This calculation checks the lug's ability to resist tearing around the pin hole.

Weld Capacity

The weld capacity ensures the lug is securely attached to the main structure.

Combined Stress Check

A combined stress check is often performed to account for multiple stress types acting simultaneously.

To perform these calculations accurately, engineers typically use specialized software or calculators. For example, the SkyCiv Lifting Lug Calculator allows users to input lug dimensions, material properties, and loading conditions to calculate capacities based on the AISC 360 ASD method1.

When designing a lifting lug, it's crucial to consider various failure modes and ensure that the lug's capacity exceeds the applied load for all potential failure modes. The allowable load for the lug will be the lowest value among all calculated capacities, ensuring safety across all potential failure modes.