Investigation of the ConXL moment connection cyclic behavior in box columns without filling concrete with different arrangement of collar bolts

The aim of this study was to study numerically the seismic behavior of ConXL connection without filler concrete of columns and reduce the number of collar bolts with different arrangement. For this purpose, to verify the modeling and analyzing, we compared the numerical results of specimens (reduced beam section, end plate and Kaiser bolted bracket (KBB) connections) with the experimental results and observed a good agreement. Afterward, 18 specimens of ConXL moment connections in box columns not filled with concrete with axial force in single, planar and bi-axial loading conditions with different arrangement of bolts were studied, and their performances were evaluated. Results show that seismic behavior of specimens with beam section depth less than W30 series under cyclic loading, even with reduces of number of bolts to 16 numbers, are suitable in the over 0.04 rad rotations. In addition, the use of 16 bolts in W30 series beams connections is suitable provided they are used in the corner connections (with single sided loading) and the material specifications ASTM-A36 are used for the beams. Moreover, the closer the position of bolts related to the outer side of collar flange, the more axial strain of bolts shank and the lesser slippage. The most optimum of bolt position is the surface middle of the collar flange and collar corner. Copyright (C) 2014 John Wiley & Sons, Ltd.