SkyCiv Weld Calculator for Directly Welded Web Connections

The calculator returns utility ratios and shear capacities for a directly welded web connection, checking the weld, the beam web and the base metal at the fusion zone.

It works to AISC 360-16 and 360-22, in either ASD or LRFD.

A simple shear connection in which the web of a secondary beam is welded directly to the flange or web of its support, usually a column or a primary girder.

No intermediate fitting material goes in: no shear tab, no clip angles, no end plate. The result is a compact, low-profile joint in which the weld deposit carries all of the vertical shear by itself.

Fewer parts to fabricate and nothing protruding into the floor zone, and in exchange a load path with nothing else to fall back on.

The part count is low, which is most of the appeal:

• Beam web: carries the shear into the joint, checked for shear yielding on the gross area and shear rupture on the net area.
• Supporting face: the column flange, column web or girder web that the beam web is welded to.
• Fillet: run along both sides of the beam web and transfer shear straight into the supporting steel.

A plate connection has somewhere else for load to go if the weld is marginal, into bolt bearing or bolt shear. This one does not, which is why the weld checks are worth running properly rather than by eye.

Where fabrication simplicity, material cost or clearance decides the detail:

• Seismic moment frames: as the secondary shear attachment, made before the full-penetration flange welds.
• Industrial platforms and crane structures: continuous welded joints hold up better than bolted ones under heavy vibration and cyclic loading.
• Tight architectural clearances: floor systems where a protruding plate or bolt head would foul cladding, services or equipment.
• Modular steel fabrication: shop-welded assemblies where automated welding is faster than fitting extra hardware.

Clearance is the constraint that tends to appear late. A detail that works everywhere else on the floor stops working where a duct or a service run passes the beam, and a welded web is often what fits in the space left.

Three checks, and any of them can govern:

• Weld shear strength: effective weld size, length and electrode strength against the applied shear.
• Beam web shear yielding and rupture: whether the web thickness and clear depth take the shear stress without yielding plastically or tearing locally.
• Base metal shear: the fusion zone on both sides, the supported beam web and the supporting flange or web, checked against base metal shear failure.

Base metal is the one most often left out of a hand check. A weld can be sized correctly and still overstress the steel it sits on, which is most likely when the electrode is stronger than the base metal.

1. Pick the design method: LRFD or ASD, whichever the project runs on.
2. Define the member profiles: standard AISC W-shapes, hollow sections or custom profiles, for both the supported beam and the supporting member.
3. Enter the weld details: size, length and electrode classification, for example E70XX.
4. Enter the design load: the applied vertical shear.
5. Calculate: utility ratios come back with the governing failure mode and the step-by-step working behind each check.

Weld size and weld length are the two inputs you will iterate. The utility ratios show which one to move.

Weld mechanics is not difficult arithmetic, but the base metal check and the web rupture check are easy to skip, and on this detail they are the ones with nothing behind them.

Running all three checks together finds the governing mode instead of leaving you to assume it. The output shows the working step by step, so a weld can be sized to what the shear actually needs rather than padded for comfort.

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