What is the primary difference between a shear connection and a moment connection?

What is the primary difference between a shear connection and a moment connection?

• A. Both connections transfer equal amounts of shear and moment
• B. Shear connection transfers primarily shear with minimal moment transfer; a moment connection transfers bending moment and provides rotational stiffness
• C. Shear connection carries bending moment, while a moment connection carries only shear
• D. Shear connection provides rotational stiffness, while moment connection does not

Answer: (B)

The key difference is how the joint handles rotation and moment. A shear connection is designed to transfer vertical (or horizontal) shear forces between members with minimal restraint to rotation, so it carries mainly shear with very little bending moment transfer and little rotational stiffness. A moment connection, on the other hand, transfers bending moment across the joint and provides rotational stiffness, making the connected members act more like a continuous frame and resisting rotation at the joint. In practice, shear connections use simpler details (like bolts in the shear plane or a basic end plate) that focus on shear transfer, while moment connections use welds or full-depth connections along flanges to resist bending and rotation. The other ideas—that both transfer equal amounts of shear and moment, or that shear carries bending moment, or that shear provides rotational stiffness—don’t fit the way these connections are designed to behave.

The key difference is how the joint handles rotation and moment. A shear connection is designed to transfer vertical (or horizontal) shear forces between members with minimal restraint to rotation, so it carries mainly shear with very little bending moment transfer and little rotational stiffness. A moment connection, on the other hand, transfers bending moment across the joint and provides rotational stiffness, making the connected members act more like a continuous frame and resisting rotation at the joint. In practice, shear connections use simpler details (like bolts in the shear plane or a basic end plate) that focus on shear transfer, while moment connections use welds or full-depth connections along flanges to resist bending and rotation. The other ideas—that both transfer equal amounts of shear and moment, or that shear carries bending moment, or that shear provides rotational stiffness—don’t fit the way these connections are designed to behave.