Clause 9 Application

Date 12-13-2017 18:48

The project we are working on is made almost entirely of sq tubing or HSS (hollow structural shapes as I understand it). Being that every weld is connected to square tubing, I interpret D1.1-2015 to mean that Clause 9 applies to every single weld. I’ve seen people argue that it may not always need to apply, such as welding a tubular post to a base plate when the only reason for using tubular rather than a beam was for convenience. I can’t see a way to completely justify making that distinction.

Looking at D1.1-2015 and reading some of the info you guys have presented, my understanding is that Clause 9 was developed with a fairly specific intent. It was originally intended to govern mainly marine applications that are subject to some cyclic loading. However, that is only in the commentary. Clause 9, by the letter, is applicable to tubular connections, which are defined as “A connection in the portion of a structure that contains two or more intersecting members, at least one of which is tubular”. It includes criteria for both cyclic and static loading.

Al has asked me in a previous post if we need to comply with D1.1. The answer I’ve gotten from engineering is that they prefer we comply with it, and it may be necessary, but we don’t have any contract documents requiring it because we are still in the design phase and have not won a bid yet.

I’ve linked to two photos below. The first shows a lap joint, a plate is to be welded on the side of a 16” wide tubular post. Does that fillet weld need to comply with the acceptance criteria in Table 9.16? I understand that it is, in fact, no different than a plate to plate connection, but it is by definition a tubular connection. The second photo shows a typical portion of the structure using 3”x3”x3/16” tubing and 1/4” plate. I’m not sure where to draw that line where Clause 9 applies and where it doesn’t. It’s a judgement call that comes with experience, I’m hoping to get some insight from you guys.

https://www.dropbox.com/s/73ciyirba93m4v3/20171213_112304.jpg?dl=0
https://www.dropbox.com/s/fzdj888j7cf4x6l/20171213_112157.jpg?dl=0

Thank you,
-Dave

By Steelslinger (**)

Date 12-13-2017 20:14

It really does not make much difference if you look at the Tables 6.1 and 9.16 against each other. Table 9.16 is identical to Table 6.1 Cyclically Loaded.

If it is stated in the Prints/Contract Docs, use whichever Table is called out. If its cyclically loaded, reference both, T-6.1 Cyclic/T-9.16. Otherwise, use whichever makes the Boss, Engineer or Owner happy.

My opinion would be to use Table 6.1 for the simple fact that you are looking at Plate Tabs welded to one side wall of a HSS member with fillet welds.

We work with a ton of HSS, W-shape and plate. On my reports I inspect and reference both.

By 803056

Date 12-13-2017 20:16

Please refer to the attachment for my comments.

Al

Attachment: 20171213_112157CommenttubetoPlate13-Dec-.pdf (207k)

By dhagfors (*)

Date 12-13-2017 20:33

Thank you guys for the help. I'll consider similar joints as plate connections, and reference Clause 9 only when they're more genuine tubular connections.