Simple W beam bolt holes widened using torch 2

[Yan3076]

Hello,

I have a simple W steel beam. It had been delivered to site with 15mm shifted bolt holes at one end only. Without asking design office, people at site widened them using torching. For me, heating this critical area of the beam (connection point) is not acceptable because steel prosperities are altered. I thought about welding connection angles to the beam beyond affected area but reaction eccentricity becomes bigger and then higher moment on support. Support is not designed for a higher moment and a new solution is necessary.

Now, I’m asking them to have a new beam but site people don’t like it because site is very far, accessible only by boats and float planes, and the project is at its last days.

What do you think? Is new beam exaggerated? What would you do?

 

[BUGGAR]

But if you weld it, won't you alter the properties of the steel also? What steel properties are you concerned with altering?

 

[Tmoose]

Hi Yan 3076,

So, the design called for three 20 mm DIA holes in the web at the end, and adjustment provided by the "short horizontal slotted holes" in the angles welded to the 20 mm thick plate?
The problem is In the field they turned the 20 mm holes in the beam web into slots to meet up with the angles' slots?
Are the web slots extending toward the short end, and does the extension result up with the bolts being installed in the correct location.
Do you have pictures of the enlarged holes, showing the quality of workmanship?
How many beams are involved?

 

[Yan3076]

Thank you Gentlemen for answering,

Buggar, it is a very good question. This is another reason I don't like to weld in this case. But when welding in general, we make a very rigid welded connection to assure a ductile rupture in the steel piece before that happens in the welded connection. I'm not a material engineer but I think it is about ductility, hardness, etc. you know with heat, there is more carbon in steel.

Tmoose, yes there are slotted now in the beam too. I'm not worried about size of holes, edge distance or even work quality. It is only about heated area around. Using torch to make or modify holes are not accepted by any code. There is only one beam.
This a very bad picture provided by site team. Now beam is installed and holes are not visible anymore.

 

[thaidavid40]

Knock off the worst of the jagged edges, and install it all as a "fully-tensioned" joint. That is, with the bolts tightened to the yield state to provide a clamping force. The ultimate failure state will probably be in bearing anyway.
Dave

Thaidavid

 

[wannabeSE]

The American Institute of Steel Construction (AISC) has an FAQ on flame cut holes at

https://www.aisc.org/DynamicQuestion.aspx?Grpid=6&QueId=1710&ste=_Preview&id=2100&type=0.

Some additional information on bolt holes can be found in section 3.3 (beginning at bottom of pdf page 33) of the Specification for Structural Joints Using High-Strength Bolts at

http://www.boltcouncil.org/files/2009RCSCSpecification.pdf.

I would be more concerned with the surface finish at the bearing surface. A slip critical or welded connection may not be a good idea if the original design assumed the slotted holes would allow the beam to rotate to prevent large moments being transferred to the embed.