Hi All,
I'm analyzing a cantilevered cruciform cross section that is subjected to a cyclic point load at it's free end. I wonder if I am able to specify an intermittent double sided fillet weld to connect the perpendicular plates forming the cruciform shape. This would save the fabricator a lot of welding and in terms of stress I believe it would be feasible. My two resources (AISC 14th Ed, Manual of Steel construction and AWS D1.1:2000) seem to be contradicting one another. In AWS, section 2.27.4, it states intermittent fillet welds are prohibited whereas table A-3.1in Appendix 3 - Design for Fatigue of AISC states a threshold stress range of 8 ksi for "shear on throat of continuous or intermittent longitudinal or transverse fillet weld". Any thoughts on why AISC would specify an allowable stress on a weld that is prohibited by AWS?
Thanks!
-Aaron
By 803056 
Date 05-13-2016 16:55
Edited 05-15-2016 01:52
AISC is a design standard. AISC takes precedence if one is designing and fabricating to that code.
AWS D1.X can be used in conjunction with any design code or standard.
You noted the allowable stress on the intermittent fillet weld is only 8 ksi. Did you compare that to the allowable unit stress of a continuous fillet weld that can be sized smaller than the intermittent fillet weld (provided the minimum size requirement, base on the thickness of the base metal) yet transmit the same total load?
Fatigue and fillets are a bad combination. Fatigue and intermittent fillet welds are worse.
Al
Beyond Al's great analysis, have you considered getting a newer edition of D1.1? I mean really, 2000? And then trying to get anything to work together between that and a newer edition of AISC 360?
Brent
