Meshed wall openings analysis model
Limitations of wall openings
- Circular openings can not be modelled in wall panels.
- If you have specified a rectangular door or window opening in a wall panel you must model the wall as a meshed wall, otherwise a "Walls with openings have a mid-pier" validation error is displayed and the analysis will not proceed.
- A "Panel contains openings - these are ignored in
design" warning will always be issued when a wall containing openings is
designed.
When you encounter this warning we recommend that you use result lines to determine the reinforcement requirements around the opening. For further details, see the topic Manage, display and design result lines, and the related video Interactive design using Result lines.
As well as taking stock of the design implications; you need also to consider if the analysis model is appropriate, as potentially it may not reflect your original intention. In certain situations the Alternative model for wall openings (described below) may prove to be a better solution.
Analysis model applied to meshed wall panels with openings
If an opening is introduced in a meshed wall, the properties of the "lintel" wall beam directly above the opening are automatically adjusted in order to prevent the panel being unrealistically stiff. The adjustments that are applied are as follows:
• wall beam properties in the lintel use the lintel depth (h2), rather than the panel depth (h1)
• wall beam nodes in the lintel are removed from the slab diaphragm
Modeling in this way the lintel becomes less stiff resulting in improved wall results when subject to gravity and lateral loading.
Alternative model for wall openings
If the presence of an opening would form a beam like strip above or below the opening, you are advised to create separate wall panels to each side of the opening and then model the strip between the panels with a connecting beam ('coupling beam').
This method can be demonstrated by considering the below example, consisting of a two story wall with a large opening at each level.
If the openings were to be created as a window and door the resulting model would be as shown:
However, by separating the wall into discrete panels and inserting coupling beams you obtain an alternative model as below:
Such an idealisation enables the panels either side of the openings to be designed for their respective forces and enables the strips between the openings to be designed as beams.
Of course, this approach will require some additional detailing, but that would have been the case anyway had the openings been added and subsequently ignored by the design.