Bolting instead of welding

[SKJ25POL]

Contractor has asked me if instead of welding some cross members(tubes) to vertial members of a steel truss they can bolt them so after repairs they can be removed and used somewhere else.

Is that acceptable? What checks I am supposed to do?

Appreciate your opinions

 

[msquared48]

Kinda hard to answer here as adequate details with the situation are lacking here...

What kind of repairs are being undertaken, and how do the tube stiffeners play into them?
What do you visualize for the connection to the unspecified truss members?

Mike McCann, PE, SE (WA)

 

[TXStructural]

It seems like a reasonable request, but someone should be paying you to redesign the repair since this is to save the contractor money, and it will take your time. In theory, the connections could be either bolted or welded, but installing a bolted connection does require drilling which will weaken the members. It sounds like this is a repair, so they may also ask to be able to flame-cut the holes, which should NOT be permitted. Holes in structural members need to be drilled to avoid creating stress risers due to irregularity of the holes and from heat causing defects in the steel.

 

[SKJ25POL]

Any code requirement on max. size of holes in members?
These vertical mostly will be compression members, any problem in this sense?

 

[TXStructural]

As a structural engineer, I would expect you to be familiar with the relevant design standards. My first reference would be AISC Manual of Steel Design. The area of allowable holes depends on the shape being drilled and various other factors.

 

[rb1957]

"so after repairs they can be removed" ... so these are temporary brackets (etc) ? if you are removing them later, think about what to do with the redundant bolt holes ? you can leave them (and let water get where it wasn't meant to, maybe) or you can fill them.

rather than an open loop discussion about what you could do, what other's recommend from their experience, etc, let's cut to the chase and you show us what you intend to do and we'll say yea or nay.

another day in paradise, or is paradise one day closer ?

 

[KootK]

[link OP]Any code requirement on max. size of holes in members?
These vertical mostly will be compression members, any problem in this sense?[/url]

You're probably ok. You'll need to ensure that P < phi*As*Fu at the net sections where the holes will be located. Unless there are a lot of holes along the length of the member, this won't likely affect your member buckling strength appreciably. It would be best to locate the cross members near the top or bottom of the vertical member lengths if possible.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[trainguy]

Are you sure that the cross members won't be needed for overall stability of your truss?

Is the truss designer aware that you are planning on removing these members?

This is a pretty dangerous question to be asking the "internet"...

tg