Alternative Support Systems for Cantilever - National Transportation ...

anchor. In order to quantify this, a recent study on tension and compression testing of signal/sign
base plates utilizing anchor bolts compared bearing areas for calculating the bearing strength of
headed anchor bolts was looked into (14). The current method utilizes a bearing area equivalent
to the head area. This was found to be a very conservative approach, with the field tests yielding
more than double the strength predicted using the equivalent bearing area equivalent to the head
area. The recommendation of the paper was to utilize the spacing between bolts and the entire
width of the embedded template as the bearing area (14). Based on this information, it would
seem reasonable to utilize the same principles to estimate the bearing area of the plate. However,
since there would be 4 bearing areas on the plate, it seems unreasonable to assume that the
bearing area would be one quarter of the plate area. In order to be conservative it was assumed
that the bearing area would be one eighth of the plate area. See Figure 3-14 for an illustration of
the bearing area comparison.
Figure 3-14. Flexural plate bearing area for side-face blowout calculations
By using this technique to calculate the bearing strength of the plate and using a moment
arm of the diameter of the centerline of the plate, an equivalent flexural strength can be
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1/8 Bearing Area
(Conservative)
1/4 Bearing Area
(Not conservative)