A Bolted Flange Plate connection consists of two steel plates that are welded to the support and bolted to the flanges of the beam to resist moment. VAConnect assumes that the Bolted Flange Plate connections possess sufficient rigidity to maintain the angles between the connected members and behave as fully restrained moment connections as discussed in the AISC Steel Construction Manual Part 12. While various simple shear connections can be used in conjunction with bolted flange plates, VAConnect uses a shear tab to resist the applied shear loads.

Design Considerations

Bolted Flange Plate connections are checked per the AISC 360-22 design specification. Bolts are used to connect the flange plates to the flanges of the beam. VAConnect requires that the same Bolted Flange Plate connection be made at the top and bottom flange of the beam (i.e. the connection will be symmetrical about the centerline of the beam). VAConnect allows the flange plates to be connected to the support with either a double sided fillet weld or a complete-joint-penetration groove weld. The capacity of the complete-joint-penetration groove welds are not checked since the strength of the joint is controlled by the base metal according to AISC 360-22 Table J2.5. The length of the weld at the support can be manually set to a value less than the width of the flange plate, which is needed for cases when the flange plate is wider than the support.

Load Distribution - Moment, Axial, & Shear

Shear is transferred from the web of the beam to the support through the shear tab connection. Since the angle between the beam and the support in a fully restrained moment connection remains unchanged under loading, eccentricity is neglected when checking limit states pertaining to the shear tab.³ To satisfy equilibrium, the moment from the eccentric shear force (eccentricity · F_v) is added to the moment applied to the connection (M_z). The axial force is assumed to be distributed uniformly to the flanges of the beams (the shear tab connection is therefore assumed to have negligible axial stiffness compared to the flange plate connections). The moment at the connection is resolved into an effective tension-compression couple acting as axial forces at the beam flanges. Finally, the forces in the flanges plates can be calculated as R = (M_z + eccentricity · F_v) / d ± F_a/2.

Limit States

VAConnect checks the following limit states for Bolted Flange Plates (refer to the program’s detailed reports for specific code references):

• Shear Tab
  • Bolt Group Capacity (Shear, Bearing, & Tearout)
  • Bolt Group Capacity (Shear, Bearing, & Tearout) - Beam Web
  • Fillet Weld
  • Base Metal
  • Base Metal - Support
  • Block Shear
  • Shear Yield
  • Shear Rupture
• Top & Bottom Flange Plate
  • Tension Yield
  • Tension Rupture
  • Tension Rupture - Flange
  • Compression Buckling
  • Block Shear
  • Block Shear - Flange
  • Bolt Group Capacity (Shear, Bearing, & Tearout)
  • Bolt Group Capacity (Shear, Bearing, & Tearout) - Flange
  • Weld
  • Base Metal
• Connection Detailing
  • Shear tab maximum plate height
  • Shear tab maximum plate thickness
  • Shear tab fillet weld maximum and minimum size
  • Shear tab number of fillet weld lines
  • Welds are adequate to developed shear tab strength
  • Shear tab and flange plate maximum and minimum bolt spacing
  • Shear tab and flange plate maximum and minimum bolt edge distances
  • Flange plate fillet weld maximum and minimum size
  • Flange plate's width-to-thickness ratio is nonslender

Limitations

• Permitted beam shapes: I-Beams
• Permitted supporting member shapes: I-Beams, Channels, HSS, Pipe, or Rectangle. The support member is only limited when importing from VisualAnalysis.
• The support element is only considered as far as it affects the weld design (e.g. base metal check, minimum and maximum fillet weld sizes)
• Weld base metal checks assume that there is not a connection on the opposite side of the support
• Beam is nearly perpendicular to the support
• A single member framing into a support
• Only a single vertical row of bolts is allowed for the shear tab
• Web yield and rupture are not supported
• Only standard bolt holes are supported
• Only forces in the plane of the connection (shear, axial, and moment) can be checked
• When an unrecognized beam is imported from VisualAnalysis, the beam’s T dimension is assumed to be the depth minus twice the flange thickness (i.e. the fillets are neglected)
• Only fillet welds and complete-joint-penetration groove weld are allowed at the support (partial-joint-penetration groove weld are not supported)
• The flange plates are assumed to resist the moment and axial load and no shear

Block Shear

The figure below shows the possible block shear failure methods that VAConnect checks at the plate-to-flange connection.