How to use the bolt spacing and edge distance calculator
How far apart the bolts sit and how close they get to the edge of a plate controls whether a bolted connection reaches its bearing strength or tears out early. Pick the nominal bolt diameter and the thickness of the thinner connected ply, enter your intended spacing and edge distance, and the tool returns every AISC 360 limit at once.
Section J3.3 sets minimum center-to-center spacing at 2 2/3 times the bolt diameter and notes that 3 diameters is preferred. Minimum edge distance comes from Table J3.4: 3/4 in. for a 1/2 in. bolt, 1 in. for a 3/4 in. bolt, 1-1/4 in. for a 1 in. bolt, and 1-1/4 times the diameter for bolts larger than 1-1/4 in.
Maximum limits matter as well. Section J3.5 caps the edge distance at 12 times the thickness of the connected part and never more than 6 in., and caps spacing for painted members or unpainted members not subject to corrosion at 24 times the thickness and never more than 12 in. Beyond that the plies separate and moisture works into the joint.
Meeting these geometry limits does not by itself prove the connection works. Bolt shear, bearing and tearout strength, block shear, slip resistance for slip-critical joints, and the strength of the connected members all still need to be verified. Have a licensed structural engineer confirm the connection detail before fabrication.
Frequently asked questions
Section J3.3 requires center-to-center spacing of at least 2 2/3 times the nominal bolt diameter, and states that a spacing of 3 diameters is preferred for fabrication and bearing strength.
The bolt tears out through the end of the plate in a bearing and shear rupture failure. Edge distance directly limits bearing strength, so the Table J3.4 minimums must be respected.
Yes. Section J3.5 caps edge distance at 12 times the thickness of the connected part and 6 in., and caps spacing for painted members at 24 times the thickness and 12 in., to keep plates in contact and prevent corrosion.