2005

Double-Angle Shear Connections with Short Outstanding Legs
The major objective of this experimental research was to investigate the behaviour of double-angle shear connections for use with a hollow structural section column having a face width less than 152mm. It was desired to prove the acceptability or unacceptability of the practice of either shortening the outstanding legs and using fillet welds or using flare bevel groove welds with full-section angles. 
  Twelve full size connections were designed and fabricated to mimic the worst scenario: double-angle connections used with a HSS 102x102 column which results in a width for outstanding legs as small as 30mm. The twelve specimens were divided into three groups. Each group consisted of four specimens having 3, 4, 5, and 6 bolts (19 mm diameter snug-tight A325 high-strength bolts), respectively.
   A 3-jack setup which was able to apply simultaneous shear load and rotation demand to the connections was employed to conduct the testing of connections under monotonic loading. Each specimen was tested in two stages, i.e., stage one under increasing rotational demand and stage two under increasing shear load while maintaining a required rotational demand. The observed physical failure modes were rupture of fillet welds, rupture of bolt group, yielding of gross section, and rupture of net section. 
     
The following conclusions have been drawn from the test results and analysis: 
1) Shear fracture of the weld group or bolt group were the most commonly seen failure modes for the test connections.
2) The major sources of connection rotational capacity or ductility were: distortion of outstanding legs, slip of bolts in web-framing leg, and bearing deformation of bolt holes on both connection angles and beam web.
3) All connections were deemed satisfactory as they were able to undergo the required rotation and were brought to their theoretical shear failure strengths without any premature failure, though shortened outstanding legs did reduce the rotational capacity.

     Therefore, the practice of either shortening the outstanding legs or using flare bevel groove welds are both acceptable for double-angle shear connections with (1) outstanding legs not shorter than 30 mm; (2) angle thickness from 6.4 mm to 9.5 mm; (3) the number of bolts not greater than 6, and (4) twice weld size top return for fillet welds and no top return for flare bevel groove weld.

Selected Publications
Gong, Y. (2007) “Double-angle shear connections with small hollow structural section columns”, Journal of Construction Steel Research. Submitted for review.

Gong, Y., and Gillies, A. (2007) “Double-angle shear connections with short outstanding legs”, Canadian Journal of Civil Engineering, In review.

Gong. Y., and Gillies, A. (2006) “Experimental Study of Double-Angle Simple Connections with Short Outstanding Legs”, Proc., the 10th East Asia-Pacific Conference on Structural Engineering & Construction, Bangkok, Thailand, August 3-5, Vol. 6, pp. 57-62.

Gong, Y., and Gillies, A. (2006) “Double-angle shear connections with short outstanding legs”, A report submitted to Steel Structures Education Foundation. July 2006.