What is the key difference between slip-critical and bearing-type bolt connections?

• A. Slip-critical relies on friction from bolt pretension; bearing-type relies on bearing contact.
• B. Slip-critical relies on bearing contact; bearing-type relies on friction.
• C. Slip-critical uses welded studs to transfer load.
• D. Slip-critical uses dynamic bolts that slip under load.

Answer: (A)

The key idea is how the load is transferred across the bolted joint. In slip-critical connections, the load is carried by friction produced by pretension in the bolts—the clamped surfaces resist sliding, so the joint holds together mainly through that friction. In bearing-type connections, the load is carried by bearing contact between the bolt shank and the holes and plates—the force is transmitted through the contact area rather than through clamping friction, so pretension plays a lesser role. So the main difference is that slip-critical relies on friction from bolt pretension, while bearing-type relies on bearing contact. This distinction helps determine where each type is appropriate based on whether preventing slip or allowing bearing interaction is more critical for the connection.