In this article (and video above), we calculate the axial load on a temporary wall to help you understand the principles behind axial load determination and enhance your problem-solving skills in this critical exam area.
A temporary wall is subjected to a wind load of 30 psf and is prevented from overturning by diagonal braces spaced at 6 ft on center along the length of the wall as shown in the figure to the right. The connection at the base of the wall at Point A is equivalent to a hinge. Ignoring the weight of the form, the axial force (lb) resisted by the brace is most nearly:
We should first consider the width of wall that each brace supports. We’re told that the braces are 6 feet on center. Therefore, the maximum width each brace will support is 6 feet.
We can then calculate the resultant wind force per vertical foot of wall from the 6 feet of width:
We can now model this as a moment problem as we can treat the uniformly distributed load as a point load at mid-height:
Next, to calculate the Axial load, we have to take into account the angle of the brace.
We do this by dividing the resultant force by cosine of the angle:
The correct answer is D.
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Anthony Fasano, P.E.
Engineering Management Institute
Author of Engineer Your Own Success