SkyCiv Single Plate Connection Calculator

The calculator evaluates capacity and utility ratios for shear tab connections, covering bolt shear, plate yield and rupture, block shear and weld capacity.

Both conventional and extended configurations are handled, to AISC 360-16 in either ASD or LRFD, which matters because the two are not checked the same way.

A single flat plate carrying shear from a beam web into a column or main girder. Most engineers call it a shear tab.

The plate is normally shop-welded to the supporting member and field-bolted to the web of the supported beam. That split is the point: the welding happens where it can be controlled and inspected, and site work is reduced to putting bolts through holes.

It occupies very little space, tolerates minor fabrication error, and speeds up erection. Those three things together are why it stays so widely specified.

• Steel shear plate: typically A36 or A572 Grade 50, sized in height, width and thickness for shear and local bending.
• High-strength bolts: a single vertical row, or several rows in extended configurations, using ASTM F3125 Grade A325 or A490.
• Fillet welds: double fillet welds joining the back of the plate to the supporting column flange, column web or girder web.
• Beam web: the receiving element, checked for bolt bearing, tear-out and block shear.

There is a hierarchy to respect here, and it is the reason proportioning matters more than raw capacity. The plate should deform plastically before the bolts or the welds fail. Get that order right and the joint keeps behaving as the simple support the frame analysis assumed.

Wherever fast field assembly is worth designing for:

• Beam-to-column flange and beam-to-column web framing in commercial office towers.
• Infill secondary floor beam connections in multi-storey structures.
• Industrial platform framing and pipe rack structures.
• Renovations and retrofits, where field bolting keeps site welding to a minimum.

AISC 360-16 design guidance (Chapter 10) splits the detail in two, and the dividing line is the distance a, from the weld line to the bolt line:

• Conventional: a is 3.5 inches or less, with 2 to 12 bolts in a single vertical line. Eccentricity on the bolt group is small, which keeps the calculation simple.
• Extended: a is more than 3.5 inches, used where the beam has to clear a column flange or some other obstruction. The longer moment arm brings in flexural yielding, flexural rupture and lateral-torsional buckling of the plate.

Those three extra checks are the practical consequence of pushing the bolt line further out. An extended tab is not a conventional tab with a longer plate; it is a different design problem, and treating it as the former is how plates end up under-checked.

• Member details: the supported beam and the supporting column or girder sections.
• Plate parameters: height, thickness, edge distances and steel grade.
• Bolt setup: diameter, grade, hole type (standard or short slotted), pitch and vertical spacing.
• Weld details: fillet weld size and electrode grade, for example E70XX.
• Design forces: the factored shear demand to suit LRFD or ASD, plus any axial force.

Calculate, and the design ratios come back with the critical failure mode and a pass or fail on each check.

The hand math on a shear tab is not hard, but there is a lot of it, and the extended case adds three checks that are easy to leave out because the conventional case does not need them.

Automating bolt shear, web bearing, block shear and plate bending means the whole set runs whether or not you remembered it was required. The output log shows the working, so a ratio can be traced rather than trusted.

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