Designing a column bearing on a beam
The Column bearing on beam type (Wizard group Hangers & bearing, mark prefix CB) checks a beam or girder where a column sits on its top flange: the column's base or cap plate (and an optional transfer plate under it) bears on the flange, and the beam web must take the concentrated force (AISC 360-22 Section J10). When the web is not adequate, ILX designs bearing stiffeners (or, if you ask for one, a web doubler).
Column on beam inputs #
- Loads: the column load P (compression positive; a negative value is uplift) and the lateral shear V at the base, as service dead and live loads (LRFD 1.2D + 1.6L or 1.4D, ASD D + L), required strengths, ASCE 7 combinations or load cases.
- Beam: the W shape and its material; whether the load is interior or near the beam end, with the distance from the end to the column centreline; whether that end is framed (a web connection). Bracing for J10.4 sidesway buckling: the largest unbraced length Lb of either flange at the load, whether the loaded (top) flange is restrained against rotation (normally yes for a welded or bolted base), whether the bottom flange is braced at the load (then J10.4 does not apply), and the beam moment Mr at the load (it sets Cr; αs = 1.0 LRFD, 1.5 ASD). Tick Bottom flange also loaded here when a support or another column acts on the bottom flange at the same section (J10.5).
- Column: a W shape (web parallel or perpendicular to the beam web), a rectangular HSS, or a bearing footprint you give (length along the beam × width). The column may be offset from the plate centre along the beam.
- Plates: the base / cap plate (length along the beam N, width B, thickness, material), and optionally a transfer plate under it. Load dispersion: 1:1 (default), 2.5:1 (web local yielding only) or none.
- Flange bending model: cantilever strip (default), the J10-1 analogy, or not checked.
- Attachment: fillet welds along both plate edges (optionally all around), or bolts in two lines through the plate and the flange.
- Reinforcement: bearing stiffeners (designed when required, none, or as entered) and an optional web doubler.
How the bearing length is found #
The column footprint over the beam web (the column depth when its web is parallel to the beam web; the column web thickness when perpendicular; the HSS dimension along the beam; or your footprint) spreads through each plate at the chosen slope: 1:1 adds twice the plate thickness, 2.5:1 adds five times the plate thickness. The spread never runs past the ends of the plate (nor the beam end). The J10 equations then add the spread through the beam flange (the 5k or 2.5k term). Web crippling always uses 1:1 (or none). The result shows lb and how it was found.
Column on beam checks #
| Check | Reference |
|---|---|
| Web local yielding (interior J10-2, within d of the end J10-3) | AISC 360-22 J10.2 |
| Web local crippling (J10-4; within d/2 of the end J10-5a/b) | J10.3 |
| Web sidesway buckling (J10-6 restrained, J10-7 not restrained) | J10.4 |
| Web compression buckling (only when both flanges are loaded) | J10.5 |
| Flange local bending and web yielding in tension (uplift only) | J10.1, J10.2 |
| Flange bending under the column (no AISC limit state; the model you choose) | Manual Part 14 strip (Example II.D-2) |
| Plate thickness (cantilever beyond the column, base-plate analogy) | Manual Part 14 / Design Guide 1 |
| Bearing of the plate on the flange | J7 |
| Plate-to-flange welds, or bolts (shear, bearing, tension, no-prying flange thickness) | J2.4, J3, Manual Part 9 |
| Compression only: connectors hold the parts in place | J1.4(a) |
| Unframed beam end: full-depth stiffener pair | J10.7 |
Bearing stiffeners carry the full column load. A pair of stiffeners and a strip of web 25tw long (12tw at a member end) act as a column with an effective length 0.75h (J10.8, J4.4); the unstiffened web checks they replace are then shown as "bearing stiffeners required". Fitted stiffeners (the default) are checked in bearing on the loaded flange (J7); otherwise the stiffener-to-flange welds carry the load. The stiffeners are also checked for J10.8 width and thickness, length, corner clips, web welds and web shear rupture along the welds.
A web doubler (J10.9) can be chosen for web yielding and crippling: yielding uses the web plus doubler thickness; for crippling the doubler is added as a compression element (Commentary J10.9: the strengths add). Its welds develop its share of the force.
Column on beam verification #
Design Example J.7 (v16.0) reproduces exactly: web local yielding 248 / 165 kips, crippling 212 / 141 kips and web sidesway buckling 142 / 94.9 kips (ILX is 0.9 % higher on sidesway buckling because the Example rounds a ratio). Example II.D-3 (V14.1) checks web yielding under a plate. The stiffener column follows a published plate-girder example within 2 %.
Column on beam limits #
- Beam flexure and shear, the column itself and the column-to-plate weld are not checked here.
- The column is assumed centred over the beam web across the beam (a transverse offset adds torsion, not checked).
- The flange bending check under compression, the plate dispersion and the doubler crippling contribution are engineering models (no AISC equation); they are stated in the calculation.
- The moment Mr is not converted when you switch units in the editor: re-enter it.