tldr: For beam connections, the two main categories are simple and moment. The common types an estimator sees are shear tabs, clip angles, end plates, gusset plates, and moment connections. The type matters because connections drive shop labor. Two jobs with identical tonnage can vastly differ in shop hours on connections alone.

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A steel connection is the assembly of plates, angles, bolts, and welds that joins one structural member to another, and it can transfer three kinds of force: shear, axial, and moment. That is the textbook line. Here is the line that matters if you price steel for a living: the connection is where the labor lives.

Tonnage is the number everyone quotes, and tonnage is the easy part. You can count beams off a framing plan in an afternoon. What you cannot see from the member list is how much shop time each of those beam ends will eat, and that depends almost entirely on what kind of connection the engineer put there.

Most of what is written about steel connections is aimed at engineering students. Forces, failure modes, AISC design checks. Useful, but it answers the wrong question for an estimator. This guide covers the common connection types and what each one actually means for fabrication cost.

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The two main beam connection categories: simple and moment

For beam-to-column and beam-to-girder connections, the two main behavioral categories are simple connections and moment connections. Simple connections are designed primarily to transfer shear while allowing end rotation. Moment connections transfer shear and bending and provide substantially more rotational restraint. Brace connections, splices, base plates, and truss joints carry different force combinations and do not fit as neatly into this two-category framework.

On the drawings, the difference shows up fast. Simple connections are the default. If a beam end has no special callout, it is almost certainly a simple shear connection. Moment connections get flagged: a solid triangle, an "MC" tag, a detail bubble pointing to a full-page section.

In the shop, the difference is money.

Most of the beam connections below are a variation on one of these two categories. The brace and truss joints get their own treatment.

Shear tab (single plate) connections

A shear tab is a single vertical plate, shop-welded to the supporting column or girder, that the beam web bolts to in the field. It is the simplest connection in steel and the workhorse of every framed building.

One plate, one weld, a few bolts. Erectors like shear tabs because the beam hangs on its bolts while they plumb the frame.

Shop view: this is your baseline. When a job is mostly shear tabs, fabrication runs fast and your labor per ton sits at the low end. Every other connection on this page is priced against it.

Clip angle connections (single and double angle)

A clip angle connection uses one or two angles to join the beam web to the support. The angles can be bolted or welded on either leg, which gives four combinations, and the engineer picks based on erection sequence and load.

A double angle carries more load than a single, at the cost of a second piece and a second set of holes.

Shop view: more handling than a shear tab. Two angles means two pieces to cut, punch, and fit per end instead of one plate. On a big job the difference between all-shear-tabs and all-double-angles is real hours, and it never shows up in tonnage.

What is a gusset plate

A gusset plate is a flat steel plate that ties braces, truss members, or multiple framing members together at a joint. If a building has vertical bracing or trusses, it has gusset plates, usually at the column base and at beam-column intersections where the brace lands.

Gussets are not glamorous and they are easy to skim past on a takeoff. That is the mistake.

Shop view: a gusset is layout-heavy work. It gets cut to an irregular shape, fit at an angle, and welded along long edges, and the brace it receives often needs its own end preparation. Braced-frame jobs surprise estimators for exactly this reason. The tonnage looks modest and the gussets quietly add shop hours the member list never showed.

Moment connections

A moment connection rigidly joins a beam to a column so the joint transfers bending, not just vertical load. Buildings use them where bracing is impossible or unwanted, which is why you find moment frames around glass storefronts, garage doors, and open floor plates.

The common variants: directly welded flanges, where the beam flanges get full-penetration welds to the column. Flange plates, where top and bottom plates bridge the joint. And the bolted end plate moment connection, where a thick shop-welded plate bolts to the column face.

Shop view: this is the expensive one. Full-penetration welds need joint preparation, preheat on heavy sections, and ultrasonic inspection after. Fit-up tolerances tighten. A single moment end can cost several times what a shear tab end costs, and a moment-frame building carries dozens of them. If you price a moment job like a shear job, the shop will tell you about it for months.

End plate, seated, and the rest

A few more types show up often enough that you should recognize them on sight.

An end plate connection is a plate shop-welded across the beam end, field-bolted to the support. The shear version uses a thin plate. The moment version, covered above, uses a thick one with more bolt rows. Shops that want to avoid field welding like end plates.

A seated connection rests the beam on an angle or stiffened seat below, with a stability clip at the top flange. Common at HSS columns, where getting bolts inside the tube is not an option.

Knife plate and saddle connections handle the odd cases: a knife plate slots into a cut in the member, a saddle wraps over the top of a support. You see them at braces, at HSS members, and around miscellaneous framing.

Shop view: each of these sits somewhere between a shear tab and a moment end. The point is not to memorize a price for each type. The point is that "how many beam ends" is a different question from "which kind of ends," and only the second one prices the job.

How to read connections on structural drawings

Connections rarely sit where the members sit. The framing plan gives you the beams. The connection information hides in three other places: the typical details, the general notes, and the beam-end callouts.

Typical details carry lines like "all connections shall be double angle unless noted otherwise." One sentence, and it just set the labor profile for the whole job.

The beam-end callouts carry the engineer's design forces. On many sets you will see markings like V195, M1280, or P260 at beam ends: shear, moment, and axial loads the connection must be designed to carry. The engineer is delegating. The fabricator's connection engineer will do the design, but the estimator has to price it first, and those numbers are the only early signal of how heavy the connection work will be.

A set with force callouts on every beam end and a page of typical details is telling you something. Read it before you bid, and if the process around this is new to you, our guide to structural steel estimating covers where connection review fits in the workflow.

Why connections decide your estimate

Counting members is the part software solved years ago. Pricing connections is the part that still separates estimators, because it means holding the typical details, the general notes, and hundreds of beam-end conditions in your head at once, under a bid deadline.

It is also the layer most takeoff tools skip. They hand you a member list and leave the beam ends to you.

The takeoff itself is the part you can hand off. Ferra reads a structural set, builds the member takeoff and tonnage, and tracks what changed across revisions, which buys back the hours you would rather spend on the beam ends and the typical details. The connection judgment stays yours, and that is where an estimator earns their keep.

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FAQs

What are the main types of steel connections?

The common types are shear tabs (single plate), single and double angle connections, end plate connections, seated connections, gusset plates for braces and trusses, and moment connections. For beam connections, the two main categories are simple connections, which transfer shear while allowing end rotation, and moment connections, which also transfer bending and provide substantially more rotational restraint.

What is a gusset plate used for?

A gusset plate ties braces, truss members, or several framing members together at a single joint. It is cut to shape, welded or bolted to the main members, and receives the brace end. Any building with vertical bracing or trusses relies on gusset plates at those intersections.

What is the difference between a shear connection and a moment connection?

A shear connection, also called a simple connection, transfers shear and allows the beam end to rotate, which is fine for most framing. A moment connection also transfers bending and provides substantially more rotational restraint. Moment connections make a frame rigid without bracing, and they cost several times more to fabricate per end.

Why are moment connections more expensive?

Moment connections typically need full-penetration welds, joint preparation, preheat on heavy sections, tighter fit-up, and ultrasonic inspection. Each of those steps adds shop or field hours that a bolted shear connection never sees. A building full of moment frames carries meaningfully more labor per ton than the same tonnage in simple framing.

Where do I find connection information on structural drawings?

In three places: the typical details, which set the default connection for the job; the general notes, which carry delegated design requirements; and the beam-end callouts, where markings like V195 or M1280 give the shear, moment, and axial forces the connection must carry. The framing plan alone will not tell you.

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