For fastener threads, should they be placed in shear or tension?

• A. Shear
• B. Tension
• C. Compression
• D. Bending

Answer: (B)

When a bolted joint is loaded to pull the parts apart along the bolt axis, the fastener must carry that load as axial tension. The threaded portion is simply part of the bolt that transmits this axial force, so the primary stress in the threads under normal loading is tensile along the bolt’s length. The clamp from tightening also helps keep surfaces from sliding, so there isn’t a primary need for resisting shear along the thread surfaces in this situation. If the joint were subjected to sideways or twisting forces, shear or bending could become relevant, but for the typical axial load scenario, the critical mode is tension in the fastener, including the threaded region.