Bolt Group Shear, Bearing and Tearout Calculator

Nominal, not the measured shank and not the hole. Shear capacity goes with the square of it while bearing goes linearly, so increasing the diameter helps the bolt more than it helps the plate — which is how a connection ends up governed by the steel rather than by the fastener.

The N and X suffixes on a schedule are not decoration. Excluding the threads puts the full shank in the shear plane and is worth about a quarter more capacity, but it depends on grip length and thread run being right — a longer grip with a shorter thread is what actually puts the shank where the drawing says it is, and nobody checks that from the ground.

A bolt through a single plate sees one plane; the same bolt in a double-angle or splice arrangement sees two and carries twice the shear at the same stress. This multiplies the bolt side only — the plies still bear and tear out on their own thickness, which is why doubling the planes so often moves the governing limit state onto the steel.

The group total here is the per-bolt governing value multiplied by the count, which assumes the load is shared equally. A group loaded eccentrically does not share equally and needs an eccentric bolt group analysis; a very long joint sheds load to its end fasteners and is reduced for length under the specification's own rule.

Both bearing and tearout scale directly with it, so the thinnest ply in the stack is the one that decides them. On a double-shear arrangement compare the single middle ply against the sum of the two outer ones and take whichever is smaller.

A sixteenth of an inch is the standard-hole clearance for the smaller bolt diameters, and it grows for larger bolts and again for oversized and slotted holes. Read the figure from the standard hole table your fabrication is working to rather than assuming one — the clear distance to the edge is measured from the hole, so this number moves the tearout answer directly.

Bearing and tearout are rupture checks and run on the ultimate strength, which trips people used to quoting yield for everything else. The default is the value for the common 50-grade structural steels; take the figure from the material specification the plate was rolled to.

The first case is the ordinary one and the basis of the published tables: hole elongation under service load is limited to about a quarter of an inch. The relaxed pair applies only where that elongation genuinely does not matter to the structure or the finishes. A long slot across the line of force is a separate provision, and its slot has an orientation the erector has to respect.

Measured on the steel, never scaled off a drawing. A plate trimmed on site to clear a stiffener has a new edge distance and a new tearout check, and a short edge distance is the single most common way a nominally adequate bolt group becomes a plate that unzips.

Tearout at an interior bolt runs to the hole in front of it rather than to a free edge, so the clear distance there is the spacing less one whole hole diameter — not less half of one, as at the end bolt. Spacing is normally generous enough that the end bolt governs, which is exactly why the end bolt is where the trouble is.