ON THE EFFECTS OF CIRCULAR BOLT PATTERNS ON THE ...

This phenomenon is attributed to the unique coupled interactive deformation of the end-plate and bolt
when circular bolt pattern is used. To illustrate this, the magnified deformed configurations of the finite
element models of both circular and square bolt patterns for the Tp1-Bd1¼-d30 connection with a medium
end-plate thickness (i.e. 1 in (25 mm)) are shown in Figure 6-10(a and b). By visual inspection, it can be
seen that near bolts undergo more deformation compared with far bolts in the connection with square bolt
pattern (Figure 6-10(b)). Indeed, the end-plate at the locations of near bolts (Bolts-2 and Bolt-3) has
separated from the column flange with visible gap. In contrast, the deformed shape of the connection with
circular bolt pattern (Figure 6-10(a)) shows less deformation, at the location of near bolts (Bolts-2 and
Bolt-3), at the same load level with the end-plate being mostly intact with the column flange at the
locations of the near bolts.
(a) (b)
Figure 6-10 End-Plate Deformation Of (a) Tp1-Bd1¼-d30-CIR And (b) Tp1-Bd1¼-d30-SQR
To further verify the above analogy, the contour lines of out of plane deformation of the end-plate from
the FE analysis are shown in Figure 6-11(a and b) for circular and square bolt patterns, respectively.
These contour lines show that the out of plane end-plate deformation at the location of near bolts (Bolts-
3) is distinctly different from that of the far bolt (Bolts-4) for the square bolt pattern of Figure 6-11(b), (i.e.
0.4 in versus 0.2 in). However, the examination of the contour lines for circular bolt pattern (Figure 6-
11(a)) indicates that the out of plane deformation at the locations of the Bolts-3 and Bolts-4 share the
same contour lines. For example, contour lines of 0.3 in and 0.4 in (7 mm and 10 mm) pass through both
the near and far bolts.
Circular Bolt Pattern Square Bolt Pattern
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