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

noticeable. Among those, Asteneh-asl [14], Adey et al. [15], Meng and Murray [16][17], and Boorse [18]
conducted experimental investigation, and Bursi and Jaspart [19][20], and Mays [21] performed a finite
element analysis to study the performance of the moment resisting bolted connections. Murray [22]
studied the end-plate behavior and bolt force distribution in both flush and extended end-plate
connections by using finite element analyses. This study indicated that in the eight-bolted extended end-
plate connections, four near bolts are fully effective, while the far four bolts are effective approximately
up to 70% of their tensile strength. Based on this study, only 6.8 out of eight bolts are considered
effective in the design of end-plate connections. Thus, the AISC design manual [23] conservatively
adopted six effective bolts for these connections.
In general, the ultimate moment capacity is the main focus in designing moment resisting
connections. Particularly, in seismic regions a balance between strength, stiffness, and ductility is at the
forefront of design philosophies. To ensure ductility, it is necessary that a yielding mechanism fully
develops before brittle failure occurs. Since fracture of the bolts will result in sudden loss of strength and
stiffness, it is common design practice to increase the bolt resistance to be greater than the other failure
modes in the connection, AISC [8].
1.2 Research Objectives
Despite the large number of research studies conducted on the behavior of the moment resisting bolted
connections, most efforts have been concentrated on the behavior of the end-plate and bolts. To the
author knowledge no studies have been conducted on the effect of the configuration of the bolt pattern
on overall connection behavior. The focus of this research is to investigate the behavior of the extended
end-plate bolted connections with unconventional circular bolt pattern configuration. A circular bolt
pattern configuration is proposed as an alternative bolt pattern for the extended end-plate moment
connection. Figure 1-2 shows a typical extended end-plate connection used in this research. The results
of this study show that circular bolt pattern may improve and enhance the overall behavior of the
connection depending on their geometric parameters.
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