The column splice design module consists of an upper and lower wide flange steel column, steel splice plates at the column flanges, and connecting bolts.

Design Considerations⁴

Flange-Plated Column Splices

Full contact bearing in flange-plated column splices is always achieved when lighter sections are centered over heavier sections of the same nominal depth group. When the upper column depth is of a smaller nominal depth than the lower column, unfinished fillers may be used to "pack-out" the gap between the column flange and the splice plate. Since no force is transferred by these fillers, they are not included in the column splice design within VAConnect.

Force Transfer

For the W-shapes most frequently used as columns, the distance between the inner faces of the flanges is constant throughout any given nominal depth group. VAConnect assumes that the ends of the columns are finished to bear on one another. The bearing strength of the projected bearing area of the column ends is much greater than the axial strength of the column per the AISC Specification and will seldom prove critical in the member design. For column splices transferring only compressive axial forces, complete force transfer may be achieved through bearing on finished surfaces and bolts or welds are only required by AISC to be sufficient to hold all parts securely in place. For this condition within VAConnect, only detailing checks are performed.

When shear and/or moment forces are applied to the connection, the limit states applicable to the strength of the splice plates, bolts, and column flanges will be calculated.

To determine the shear force on each bolt, the vector resultant of the direct shear force and the rotational shear force is calculated as shown below. Because the centroid of each bolt group is eccentric to the column ends, there will be a moment on each bolt group due to the applied shear force taken at the column ends.

To determine the tension force on each splice plate, the moment about the column's strong axis (Mx) is decoupled into a tension and compression force using the width of the lower column and added to any applied tension force.

Limit States

VAConnect checks the following limit states for Column Splice connections (refer to the program’s detailed reports for specific code references):

• Splice Plates
  • Shear Yield Capacity
  • Shear Rupture Capacity
  • Tension Yield Capacity
  • Tension Rupture Capacity
  • Block Shear Rupture Capacity
  • Flexural Yield Capacity
• Bolts
  • Shear Capacity
  • Bearing Capacity at the Bolt Holes - Splice Plate, Upper Column, Lower Column
  • Bolt Tearout Capacity at the Bolt Holes - Splice Plate, Upper Column, Lower Column
  • Bolt Pryout - Splice Plate
• Column Flanges
  • Block Shear Rupture Capacity

Note that when a net tension force is present in the splice plates, the limit state of interaction between the tension, shear, and flexural forces is not considered and will need to be calculated outside of the program.

Design Assumptions

VAConnect makes the following design assumptions for Column Splice connections:

• The upper column is assumed to be centered on lower column.
• The upper column is assumed to be finished to bear on the lower column (i.e. splice bolts/plates are not required to transfer compressive loads).
• The shear force parallel to the column's weak axis is resisted through weak axis flexural bending of the splice plates.
• The frictional resistance between the upper and lower columns due to dead load is conservatively ignored.

Limitations

• The upper column depth must be within 2 inches of the lower column depth.
• The splice plate width cannot exceed the width of the upper column flange.
• The presence of erection holes or pin holes for lifting devices are not considered.
• Column stability during erection is not considered.
• Column lengths are not considered.
• Only wide flange column shapes are permitted.
• The location of the column splice is not considered. Where possible, column splices should be located at least 48 inches above finished floor elevation to accommodate the attachment of safety cables.
• Only standard bolt holes are supported.
• The bolt gauge is not checked against the column's workable gauge.
• Bolt entering and tightening clearances are not checked.
• Interaction between tension, shear, and flexural forces in the splice plate is not considered.