The double angle connection is one of the simple shear connections set out in Part 10 of the AISC Manual, and a fabricator favourite at beam to column web connections.
It consists of two angles, one each side of the beam web, bolted or welded to the beam web and to the support. On a beam to column web connection the angles are usually welded to the beam and bolted to the support. That combination needs a shorter leg on the support side, which matters when the space inside the column web is tight and an all-bolted detail would need clearance for a wrench.
An all-bolted double angle is the usual choice at a beam to girder connection, particularly where a single angle will not carry the shear: the second angle gives the support bolts two shear planes instead of one.
The three arrangements are all-bolted, bolted with the angles welded to the supporting beam, and bolted with the angles welded to the support. Where the angles are welded, weld returns are required across the top of the angles per Specification Section J2.2b.
What Governs the Design
The double angle is popular because it goes together in the field with ordinary tools and needs no special fabrication. Designing it still comes down to a handful of things that interact.
Bolt spacing drives the bolt group. Too few bolts and the bolts and angles are overstressed; too many and you are paying for a connection that is harder to install than it needs to be. Edge distances matter for the same reason, both from the angle edge and between adjacent bolts, since a short edge distance fails in tear-out long before the bolt fails in shear.
The angles themselves deform. A simple shear connection has to rotate as the beam end rotates, and the angle legs bend to let it. That flexibility is the point, but taken too far it turns into lost capacity and overstressed bolts, which is why the angle thickness and leg length are as much a part of the design as the bolt group.
The design also depends on how the beam is supported. A simply supported beam and a continuous beam put different demands on the same detail.
Designing a Double Angle Connection in SkyCiv
The design code can be AISC 360-16 ASD ou LRFD, and units English/Imperial or SI/Metric. Orientation is BCF, BCW ou BBW; hover the tooltip for what each one means. Clique le “Angle double” tuile.
Détails Onglet
Record the project details here. None of it changes the calculations, but it carries into the report.
Onglet Assemblage
Three tabs sit under Assembly: the Column, the Beam, and the Connection, which holds the double angle.
Onglet Colonne
Specify the section and material grade of the column. A992 and A36 are in the list; for anything else choose Custom and enter Fy and Fu.
Onglet Faisceau
The same inputs for the beam, plus cope dimensions and beam clearance. Add a cope where the beam frames into a supporting member of similar depth and the flange has to be cut back, since the coped section governs checks the uncoped one does not.
Onglet Connexion
Set the angle properties: grade A36 or A992, or Custom with your own Fy and Fu, then the section size and length. Where the angle has unequal legs you can switch which leg goes where. Pour BCW, put the shorter leg on the column side, because that is where the space runs out.
Watch the 3D renderer as you go. The angle height should sit within the beam depth, and the total angle width should not exceed the column T-dimension or the clear web depth.
Fixation 1 Languette
This is the angle to beam web connection. It can be bolted or welded; this walkthrough uses welded, since for BCW a welded-to-beam, bolted-to-support double angle is the arrangement that fits the column web.
Specify the weld material, or choose ‘Custom’ and enter Fnw if the electrode you want is not listed. Then the weld size. Keep the weld size no larger than the angle thickness, or there is no room to lay the weld.
Fixation 2 Languette
This is the angle to support connection, whether that support is a girder web, a column flange or a column web. Bolted or welded again; this walkthrough uses bolted.
Première, the bolt hole types at the beam and at the angle. Fabricators usually ask for standard holes (MST) in the member and horizontal short-slotted holes (CSSS) in the angle, which buys fitting tolerance in the field.
Prochain, the bolt material or grade: A307, A325, A490 or Custom. A325 and A490 are grades within ASTM F3125, which consolidated the older standalone specifications. Between N and X, X gives the larger bolt shear capacity, but the threads must be excluded from the shear plane, and the erector has to know that.
Then the bolt diameter, from 5/8″ to 1-1/2″ or the metric equivalents, and the arrangement, Jusqu'à 12 rangées et colonnes de boulons, with the row and column spacing.
Worth knowing: if you need more bolt group capacity, opening up the spacing can do it instead of adding bolts, as long as the angle height still fits within the beam depth. The bolt group strength uses the instantaneous centre of rotation method (ICOR), so a wider spacing is credited with the capacity it actually provides rather than rounded down to a table value. Check with your fabricator first, though. Many prefer 3″ spacing typical throughout and will price variable spacing accordingly.
Ce logiciel “bord” input here is the horizontal distance from the centre of the beam to the nearest bolt.
For more on the fastener side, see the documentation on boulons et soudures.
Onglet Charges
Enter the vertical shear under ‘Fy’.
Match the load to the design method you picked at the start. LRFD takes factored loads against design strength; ASD takes service loads against allowable strength. The software cannot tell which you typed.
Onglet Résultats
Cliquez sur “Exécuter des vérifications de conception”. Anything missing from the earlier tabs is flagged here rather than silently defaulted.
The summary shows whether the connection passed, with a utilization ratio against each check. S'il a échoué, change the inputs on the earlier tabs and click “Réexécuter les vérifications de conception”. When it passes, “View Calculation Report” opens the detailed report.
That is an extract from the report. Each check carries its reference to the AISC manual or specification, and the working follows the same order the specification uses, so a reviewing engineer can read it line by line instead of reverse-engineering a number.
Voici une copie PDF du rapport de calcul détaillé complet: Rapport de conception de connexion.
Try It Yourself
Pick the double angle, enter your sections, angle size, bolts and shear, and see every check with its code reference. Il s'exécute dans le navigateur, with nothing to install.
See also the double angle connection calculator et la connexions de cisaillement overview.
