ASDIP RETAIN is a structural engineering software to design retaining walls. However, the software is so flexible that it can also be used to design a masonry fence wall exposed to wind. This article shows the steps required for a fence wall design using ASDIP RETAIN.
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Fence wall design example
As an example, consider the fence wall shown below. The wall is exposed to wind loads of 47 psf in addition to its selfweight. Design the foundation for stability and calculate the required reinforcement of the masonry wall.
The first obvious step in the software is to set the backfill height to match the soil cover at the toe side. This will model a flat surface at both sides of the wall. In this example let's set this soil cover to 1'-0".
The fence wall will be modeled with 12 rows of 8" wide x 8" high concrete blocks, so that the exposed wall height is 7'-0", as shown. The shear key dimensions will be set to zero, since it's unlikely that a fence wall will have sliding problems.
In the Loads tab enter the wind pressure. Note that this needs to be calculated independently. Since the ASCE 7-10/16 load combinations have been selected, the wind pressure is ultimate. This value has been specified in this example for illustration purposes only.
Note that the wind height is 7.00 ft, which matches the exposed stem height. For simplicity, no other loads have been specified in this example.
The image below shows the stability analysis in ASDIP RETAIN. The safety factor for overturning, sliding, and bearing are greater than the minimum allowable values.
For illustration purposes, the footing length has been specified as 3'-0", which is giving acceptable results. Please note that the designer can reduce this dimension further to optimize the design.
Once the overall dimensions have been set for stability, it's time to design the reinforcing steel for the footing and the stem. In this case let's use only #4 rebars for simplicity during construction.
The image below shows the moment and shear diagrams of the stem, in red lines, for the controlling load combination. For comparison purposes, ASDIP RETAIN shows the structural capacity represented by the shaded blue areas. In this example the provided capacity is greater than the required capacity along the stem.
The image below shows the construction views, in section and elevation, of the designed wall.
ASDIP RETAIN is a flexible and powerful software that allows to design fence walls as well. Once the loads are entered, the design can be completed and optimized in minutes.
For engineering background, please read the blog post Cantilever Retaining Walls: Overview of the Design Process. For our collection of blog posts about retaining walls please visit Structural Retaining Wall Design.
Javier Encinas, PE
ASDIP Structural Software