What percentage of the stiffener bearing cross sectional area must be in contact with the inner surface of the flanges?

The requirement that 75% of the stiffener bearing cross-sectional area must be in contact with the inner surface of the flanges is based on structural integrity and load distribution principles in welding and metal fabrication. This percentage ensures a secure connection between the stiffener and the flanges, which is critical for maintaining the strength and stability of welded structures.

Adequate contact area helps in effectively transferring loads and reducing the risk of failure due to stress concentrations or inadequate support. A higher percentage of contact area minimizes the possibility of gaps which could lead to stress points that might compromise the integrity of the weld over time.

In design specifications and standards, achieving this level of contact is often mandated for compliance with safety regulations and performance expectations of welded assemblies, especially in critical applications where strength is paramount. Thus, emphasizing the importance of having at least 75% contact area helps ensure that the structural elements work together effectively under load.