Question

NOTE: This question refers to Steel Design. You may need to refer to the AISC Steel Construction Manual (you can google an older version if needed).

For bolted connections, what are the differences of bearing-type and slip-critical connections?
What are the typical limit states we should check for bolt connections? Please be as detailed as possible.

Answer 1

(A). Differences of bearing-type and slip-critical connections:

1. Bearing-type connection:

• In bearing-type connections, bolts are subjected to shear and the connecting or connected plates are subjected to bearing stresses.
• Bearing type connection can fail in several failure modes such as- shear failure of the bolts, excessive bearing deformation at the bolt holes in the connected parts, edge tearing or fracture of the connected plate, failure of member being connected due to fracture or block shear.
• In bearing-type connections, bolt threads may be included in or excluded from the shear plane.

2. slip-critical connection:

• Slip-critical bolted connections can fail in two ways; slip at the connection and bearing failure of the connection.
• Slip-critical connection must be designed to resist slip at service load and resist bearing or shear.
• This type of connections can be installed with such a degree of tightness that it should resist large tensile forces in the bolt and clamp the connected plates together.
• The connection can resist the shear force using friction if the applied shear force is less than the friction that develops between the two surfaces, then no slip will occur between them.

(B). Typical limit states check for bolt connections:

Following are the limit state checks needed for bolted connection-

• Shear capacity of boli: Shear capacity is controlled by one of two limit states; slip and shear rupture
• Tensile capacity of bolt
• Bearing capacity of bolt and plate
• Tension or tearing rupture capacity of plate
• Shear capacity of plate
• Block failure check