{"id":33703,"date":"2026-04-27T12:59:35","date_gmt":"2026-04-27T12:59:35","guid":{"rendered":"https:\/\/protasoftware.com\/technical-manuals\/structural-modelling\/castellated-beam\/"},"modified":"2026-06-19T12:37:45","modified_gmt":"2026-06-19T12:37:45","slug":"castellated-beam","status":"publish","type":"wiki","link":"https:\/\/protasoftware.com\/wiki\/castellated-beam\/","title":{"rendered":"Castellated Beam"},"content":{"rendered":"
\n

A castellated beam is created by slicing an I-beam longitudinally along
\nits web in a specific pattern. The goal is to separate and then rejoin the beam
\nwith a deeper web. These beams are categorized based on the shape of the
\nopenings in the web section, with common shapes including hexagonal, circular
\n(also known as cellular), octagonal, and diamond.<\/span><\/p>\n

<\/span><\/p>\n

Additionally, castellated beams are useful in situations with height
\nlimitations. The openings in the beam web allow for easy passage of piping.
\nHowever, these benefits come with trade-offs. The web openings introduce
\nadditional failure mechanisms, necessitating checks such as Vierendeel,
\nhorizontal shear, vertical shear and web post shear buckling. Furthermore, the
\nsection properties used in finite element analysis differ from those of
\nconventional solid beams.<\/div>\n<\/p>\n
<\/div>\n<\/div>\n
\n
<\/div>\n

Inserting a Castellated Beam<\/span><\/span><\/a>
<\/h2>\n
\n

To insert a castellated steel beam:<\/span><\/p>\n

1. <\/span>Pick the Steel Beam command on the <\/span>Modeling > Frame<\/b> ribbon tab.<\/span><\/div>\n
<\/div>\n
<\/span><\/div>\n
<\/div>\n
2. Insert a linear<\/b> or curved<\/b> frame member as usual.<\/span><\/div>\n
<\/div>\n
3. <\/span>On the Frame
\nProperties<\/b> window, switch to Castellated<\/b> tab.<\/span><\/div>\n

<\/span><\/p>\n<\/div>\n

<\/div>\n
<\/div>\n
4. You can select a Hexagonal<\/b> or Circular<\/b> Opening.<\/span><\/div>\n
\n
\"Notes\"<\/p>\n
The code design
\nformulations are given for circular (cellular) and hexagonal openings, thus rectangular openings are not supported.<\/div>\n

<\/span><\/div>\n

<\/div>\n<\/div>\n<\/div>\n
5. Place the openings
\nby specifying their Count or clear Spacing. You can also specify Start
\nOffset and End Offset.<\/div>\n
<\/div>\n
\n
<\/p>\n
6. Also specify the
\ndimensions of the web openings using the Width<\/b>, Height<\/b> or Diameter<\/b> fields.<\/div>\n

<\/span><\/div>\n<\/div>\n

\"Alert\"<\/p>\n
Important:<\/span><\/div>\n
While inserting the castellated steel
\nframe member, choose a hot-rolled profile or built-up profile that will
\nhave the final profile depth. <\/div>\n
If the final profile will have 460 mm
\ndepth after slicing and welding, then choose, for example, a W18x46 hot-rolled
\nprofile, instead of the original profile before the cut.<\/div>\n

<\/span><\/div>\n

\n
<\/p>\n
<\/div>\n
7. You may want to infill
\nsome of the openings, in this case specify the number of openings to be infilled
\nin respective order. For example, if you want to infill second, third and fifth
\nopening you can enter 2, 3, 5<\/b> in the Closed Holes<\/b> field. This
\ndoes not have any effect on analysis or design. It can be used for detailing
\npurposes.<\/div>\n

<\/span><\/p>\n<\/div>\n

<\/div>\n
<\/div>\n
<\/div>\n
\n

Design of Non-Composite Castellated Beams<\/span><\/span><\/a>
<\/h2>\n
Due to the presence of the significant number of web openings, castellated
\nand cellular beams cannot be treated as solid-web members or members with web
\nopenings. These structural members are highly indeterminate elements, which do
\nnot lend themselves to a simple method of analysis. The following limit states
\nshould be investigated when designing castellated or cellular beams:<\/span><\/div>\n
    \n
  1. Compactness and local buckling<\/span><\/li>\n
  2. Overall beam flexural strength<\/span><\/li>\n
  3. Vierendeel bending of tees<\/span><\/li>\n
  4. Web post buckling<\/span><\/li>\n
  5. Axial tension\/compression<\/span><\/li>\n
  6. Horizontal shear<\/span><\/li>\n
  7. Vertical shear<\/span><\/li>\n
  8. Lateral-torsional buckling<\/span><\/li>\n<\/ol>\n

    <\/span><\/p>\n

    The first step in designing both castellated and cellular beams is to
    \ncalculate the overall bending moment and shear force at each opening and web
    \npost caused by external loads. These forces will be referred to as global
    \nforces. The global forces will be used to compute localized forces in the top
    \nand bottom tees, the web posts, and the gross section. The components (tees and
    \nweb posts) of the beams will then be examined for failure under the localized
    \nforces.<\/span><\/p>\n<\/div>\n<\/div>\n

    \"Alert\"<\/p>\n
    \n
    Important<\/div>\n
    ProtaStructure 2026 performs castellated beam checks according to Eurocode 3<\/b>, AISC360<\/b>
    \nand Turkish Steel Design Code.<\/b> <\/div>\n

    <\/span><\/div>\n
    ProtaStructure
    \ncurrently supports only the non-composite castellated beams. 
    <\/span><\/div>\n
    \n
    \n

    [Reference: AISC Design Guide 31 \u2013 Castellated and
    \nCellular Beam Design<\/i>]<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n

    <\/span><\/div>\n

    \n
    \n

    <\/span><\/p>\n

    Analysis results shown for a model including castellated non-composite castellated beams<\/i><\/span><\/font><\/div>\n
    <\/div>\n
    <\/div>\n
    <\/span><\/font><\/div>\n
    \n

    Castellated Steel Beam Design UI and Detailed Report in ProtaStructure<\/i><\/span><\/p>\n

    <\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n

    Detailing<\/span><\/span><\/a>
    <\/h2>\n
    The web openings are automatically communicated to ProtaSteel for
    \ndetailing. Openings are defined by cut object, so you can modify them easily if
    \nneeded.<\/span><\/div>\n
    <\/div>\n
    <\/div>\n

    <\/span><\/div>\n<\/div>\n
    \n
    \n
    \n


    <\/span><\/p>\n<\/div>\n

    <\/div>\n<\/div>\n

    \n

    <\/div>\n
    <\/div>\n<\/div>\n
    <\/div>\n
    \n


    <\/span><\/p>\n<\/div>\n

    <\/div>\n","protected":false},"excerpt":{"rendered":"

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