equivalent weld for stair treads

Date 08-07-2010 09:28

dlmann
Not enough information but that is up to the engineer, does the job require the stair manufacture to engineer the stairs or is the customer's Engineer responsible? Submit a R.F.I. Request for information
Are you using the same plate for connection?
Good Luck
Marshall

By 803056

Date 08-07-2010 16:47

It is the EOR's responsibility to verify any options elected by the fabricator are viable before granting approval.

It is not the inspector's responsibility to take on engineering or design responsibilities. To do so is a sure way to end a career as an inspector.

The "approved" drawings should have the required weld size, length, number of welds, etc. indicated on the drawing. If the information is missing or if the drawings are not stamped by the EOR, the inspector has no business or authority are accept the welds. Go back to the engineer for clarification and a stamped revised drawing or sketch.

Stairs are tricky business. Stairs and fire escapes were the only things my insurance policy would not cover. The insurance company's position was that there is no easy way to determine the loads on the stairs when they were most critical, i.e., when there is an emergency and everyone is trying to go down the stairs to get out of the building.

Remember the Kansas City Hyatt Regency Walkways Collapse. Here is a excerpt from something I found on the internet:

Best regards Al

HyattRegencyWalwayCollapse_Page_1.jpg (198k)

By G.S.Crisi (****)

Date 08-09-2010 23:52

Gentlemen,
I may be wrong, for English is not my mother language, but from what I've understood of Donnie's massage he's not saying that he's the inspector. He's just asking for help on how to replace structural steel bolts with welding. Chances are he's the engineer in charge of that task and before taking a decision would like to know sound opinions from qualified people, as this Forum frequentors.
Donnie, I'm not a structural steel engineer, so I can't be of help to you. Why don't you try the AISC site? They're the great specialists on structural steel, or, as we say in Brazil, the Popes on structural steel. Here in Brazil, when someone knows a heck of a lot about a subject, we say that "he's the Pope on that subject".
Another idea. Someone (I don't remember who, must be Henry) attached the Code on Structural of the State of New York to one of his postings. Click on Search and try to find it out. Good luck.
American Institute of Steel Construction site: www.aisc.org
Giovanni S. Crisi
Sao Paulo - Brazil

By 803056

Date 08-11-2010 03:40

Hello Giovanni;

My take of the situation was that the fellow isn't an engineer, but more likely a third party inspector. You might be correct in your assessment. It would not be the first time I managed to step into a mess.

Best regards - Al

By TimGary (****)

Date 08-11-2010 13:17

When erecting metal buildings according to AISC requirements, often welds are used to replace bolts in cases where bolt holes don't line up on secondary structures. In these cases, we always used the rule of thumb that was provided by our Engineer, that a 1" long, ER7018, 3/16" fillet weld will replace a 1/2" A325 bolt. However, any time we had to do this, we would get a signed and stamped repair procedure from the Engineer for back up.
If I were an Engineer making this determination, which I'm not, I would start with determining the amount of load the bolts are theoretically being subjected to, then calculate the size and length fillet weld required to handle the same load, and add a considerable safety factor. I would also think very seriously about requiring the contractor to submit a WPS for prior approval and CWI visual inspection of these completed welds to ensure compliance.
Tim

By 803056

Date 08-12-2010 13:55

I agree with your take on the post. It isn't the inspector's responsibility to size the fillet welds required to replace the bolts.

Calculating the strength of a fillet weld isn't complicated, however, it is beyond the inspector's training (as an inspector) to fully comprehend or appreciate the complexities of different loading conditions and the interaction of several welds sharing a load.

A quick look at Clause 2.5.4.3 of AWS D1.1 (2006) where they discuss the instantaneous center of rotation of multiple welds in a group should convince any inspector such mathmatical gryrations are best left to the design professions. That is exactly why changes, even "small" changes, should be reviewed and approved by the responsible design professional, not the welding inspector.

Best regards - Al

By dlmann

Date 08-12-2010 19:17

Thanks Al and everyone else for the input. This happened in my plant. We have ten thousand stairs here and all bolted. We are putting a new system and it has one set of stairs. The contractor fabbed the stairs off site and welded in lieu of bolting based on the detail in the drawing for 3/8 bolt or equivalent weld. When asked about weld size and length, their answer was “this how we always do it, its in D1.1”.
Before I shout “foul”, I needed to know what the foul was before pushing it up the chain. The contractor should not have welded without approved weld details and when he did weld, he couldn’t back up the why and how questions. Engineering calculated the equivalent weld size and length and after some additional weld metal the stairs were accepted. A comment about this should be placed in the evaluated suppliers list.
Regards, Donnie Mann