Question about "main beam" in shop build

[dcs13]

Most buildings I see use a "bolt up" main beam structure. 2 posts and a 2 piece beam spanning the center of the build. I rarely see these main beams welded up. Is there a reason other than its easier to weld flanges in the shop and bolt it up on the job site ?

 

[The Cobbler]

probably easier , less cost . no need to bring a welder & a welding machine to the jobsite , and no worries about wind & weather conditions on the day they plan to weld.

 

[kwb]

Field welds are expensive compared to a small box of bolts. Typically in the trades for commercial work - Welders weld and that is about it. They command a pretty good premium so it makes sense to not have them around a lot or have them doing tasks that don't bill out at that rate. A lot of the time it is also necessary to have a 3rd party CWI inspect to get buy-off on permitted work.

Even with really bad torque control, the engineer can make a prediction that it will meet minimum standards. Most anyone can read the markings on the heads of the bolts to verify they meet spec.

 

[MBfreak]

Welding in a building with lots of wood structures and maybe also less than perfect housekeeping is a fire hazard. Welding spats creep everywhere and onset that is visible may be several hours later.

Ola

 

[readhead]

As an erector it is much easier and faster to bolt up than weld. Spending some shop time at the front saves a lot of labor at the back.

 

[cvairwerks]

We did a couple weldup main beams when I did steel building work. Took a lot more time and equipment to get them finished and up into place. Get past a certain length and now you need bigger cranes and spreader bars to handle the weight and twist. The last one I worked, required a pair of 75 ton crawler cranes to lift into place and we were on hold for 3 days due to wind issues. Couldn't do the lift if winds were over 5 mph, due to the reach required and the crane positioning. Had it been a boltup beam, we wouldn't have had to worry and could have had one smaller crane hold the center joint as we lifted the halves with our forklift.

 

[dcg9381]

Here, it's 20-30% more expensive to assemble a "bolt up" building. Why? Precision is required. The welders can weld a lot faster than you can bolt things together. Weld up they just weld up and trim...

Advantage of a bolt-up seems to be that it can be considered an "engineered structure" and a stamp provided from the building supplier (Mueller).

 

[readhead]

Your missing the part of a weld up building where the time is spent detailing, layout and cutting the parts. A bolted connection will go together faster than a welder can weld on a similar sized joint.
I think I can say that with confidence after forty plus years as a welder and erector.

 

[dcs13]

Thanks for the replies guys... I'll post pics when my shop is done in a few months. Im a little slow

 

[brownbagg]

3rd party CWI inspect

thats me