double angle web cleat joist connection-steel erection problems? 1

[IJR]

I usually specify double angle web cleats for connection of joists to main beams in shear connections, aiming at taking advantage of a gap available between beam and joist at joint interface for easy fit.

In addition I usually spend considerable design time to make joists short and light. In other words, many light joists, figuring out that it will be easier to place many light joists that it would be to keep a few heavy joists in place.

Erection teams keep complaining that the connection takes too much time.

Should I design one angle cleat web connection? Is it something to do with techniques the erectors use?.

I detail to simplify things but I am not an expert erector, so any comment will do

Regards
IJR

 

[Ron]

IJR...I hope I am not missing something in your description, but typically, open web joists are attached to the top flange of the beam, not to web cleats. While reducing the span and spacing of the joists is commendable, it does create more labor and effort in erection. As an example, you will need the same crane to lift an 18K joist as you would need to lift a 12K joist, but since you would have more of the 12K's by necessity for the same loading, you will have more lifts, more movements, more chance of accidents, more connections, etc.

Erectors prefer to be able to walk the beam and bend over to weld open web joist seats with a quick fillet weld. If they are welding to a web cleat, they must sit on the beam, lean over and weld in a more difficult position, again slowing their progress.

 

[IJR]

Thanks Ron for the fast response at early morning hours. Sense of responsibility is one of your top qualities boss.

You seem to be favoring a few heavy platform beams to many light beams. Accepted that line of thought.

As for joists you are 100% right in that they are best kept on top of beams. However my situation is usually very limited floor depth and I have to keep the elevation of both beam and joist(when I say joist I actually mean secondary beam in our usage here) the same.

Thanks once more and again Ron, and wishing you all the best.

Respectfully
IJR

 

[Ron]

IJR...thanks, I understand the condition now.

For this condition under somewhat lightly loaded conditions, you might consider a single vertical angle cleat on each side of the web of the primary beam, with the secondary beam flange coped to fit the primary beam. For this connection you could use bolts instead of welding. A three-bolt clip is common in this application.

Obviously this connection could be welded, but you would have to weld in the vertical position which is more difficult and requires more stringent certification of the welder. The shop welds on the cleats would be put in with the primary beam on its side, thus would be in a flat or horizontal configuration, resulting in better quality weld and less effort.

Erection of this configuration is relatively easy as the secondary beam is usually tilted and dropped in between the primary beams, then rotated into position on the flat side of the angle.

Double cleats on the same side of the web are difficult to erect as you have little "wiggle room" to "knife" the web of the secondary beam in between the double cleat.

Ron