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

deformed shape contour lines showed that the end-plate contour lines at locations of the near and
far bolts are more condensed, closer to each other, for the connections with circular bolt pattern,
thus the end-plate deforms more uniformly at the locations of the near and far bolts. This results in a
more uniform distribution of the bolt force between the bolts in the connection.
Tri-linear hysteresis model was used to simulate the behavior of the connection. To predict the
hysteresis characteristics of the connection the hysteresis behavior was divided into two categories:
“End-Plate Behavior” and “Bolt Behavior.” The proposed tri-linear hysteresis models are different
from what are commonly found in the literature. The proposed models promise a better prediction of
the hysteresis characteristics of the connection and reduce the degree of un-conservativeness.
The tri-linear model equations are developed based on four parameters (i.e., My, E, Et, and θf). For
each of the above parameters (dependant variables), prediction equation were developed using a
non-linear regression analysis. These equations are in term of connection dependent geometric
variables (i.e., bd, tp, S, and Z).
The results obtained from the prediction equations were compared by the true value for each
connection using corresponding independent geometric variables. This study was conducted on
connections with both circular and square bolt pattern separately. The results of this comparison
show that majority of the predicted variables fall into ±5 error envelope when they are compared with
the true value of the corresponding connection. Therefore, the developed equations proposed as an
alternative method to model the hysteresis characteristic of the extended-end-plate connection.
Using the predicted dependent variables and the proposed hysteresis models introduced in this
research the predicted hysteresis for each connection was graphed against the hysteresis results
obtained from the finite element models. The comparison of the presented results shows satisfactory
agreement between the predicted and true behavior of the connection.
7.3 Recommendations
The parametric study conducted in this research was limited to seven bolt diameters, six end-plate
thicknesses, three beam sizes, and two different bolt pattern configurations, while other important factors
that affect the overall behavior of the connection was neglected. Further investigation with more
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