Bolt with spacers securing I-beam to floor

[DaveC426913]

TL;DR Summary

What could be the purpose of these spacers?

Found this on an I beam in a light industrial park converted to a retail store.

What function do the spacers serve?
They seem counterproductive by creating a greater moment arc to get ripped out.

Or rerhaps they compress a little, allowing the building to flex and not shear the bolts off?

 

[.Scott]

My guess is that there was originally something else bolted down there. That something was removed, but because usable thread were not available below where the bolt is seen, spacers were required. The spacers used were improvised.

 

[DaveC426913]

An interesting hypothesis.

 

[Baluncore]

That looks more like a universal column, UC, than an RSJ, taper flange beam.
The bolt is there to prevent the base moving sideways, or lifting and rattling in strong winds.

The rag bolts were set in the concrete footings before the slab was poured. To be sure to protrude, the bolts were given excess length. The rag bolt was then too long to be tightened using a shallow socket and ratchet wrench, without the use of multiple washers.

Cutting the rag bolt to length was difficult and unnecessary. Using an open-ended spanner in that restricted space would have been slow and more expensive in time than the packing washers, especially if the threads were spattered with concrete.

 

[tech99]

I suspect the bolt had insufficient thread.

 

[Baluncore]

I suspect the bolt had insufficient thread.

To determine the length of available thread, x-ray the column base, or undo the nut.

 

[DaveC426913]

It occurs to me I do not know those things are spacers. I am assuming they're unthreaded, but I have no evidence to base that on. For all I know they're just square bolts.

 

[DaveC426913]

To determine the length of available thread, x-ray the column base, or undo the nut.

Both of those might be frowned upon by the current occupants of the space.

 

[tech99]

I think the rag bolt (or similar) is to locate the base in position. They are probably not subject to great loads. If the beam was at any time, for instance during strong wind, subject to uplift then I would have more concern, because the rag bolt might not have sufficient depth into the concrete.

 

[gmax137]

Construction jobs are all about getting done in minimum time. Whining to your foreman ("waah, the bolts are too long!") is seen as a weakness. Bump in the road? Figure it out and get it done...

Edit: "cut to suit, beat to fit, paint to hide."

 

[.Scott]

It occurs to me I do not know those things are spacers. I am assuming they're unthreaded, but I have no evidence to base that on. For all I know they're just square bolts.

The top spacer, the one in direct contact with the nut, has flexed - in apparent reaction to the tightening of that nut. If it was a threaded nut with threads that mated with the bolt, it would have supported that top nut where that nut made contact with the bolt and it would have likely been made of a hardened metal. Both of those conditions would make it very unlikely that it would have reacted with that kind of bend.

Here's a normal construction geometry.

Note the use of square washers.

Also, not that it is typical for the bolt to extend well above the floor - and for it to be completely threaded from the floor up.

What is likely is that the threading became damaged and unusable.

 

[DaveC426913]

Here's a normal construction geometry.

Note the use of square washers.

Excellent demo.

Also, not that it is typical for the bolt to extend well above the floor - and for it to be completely threaded from the floor up.

What is likely is that the threading became damaged and unusable.

Very cool. Thank you.

 

[Baluncore]

What is likely is that the threading became damaged and unusable.

Very cool. Thank you.

Did you notice that the threads in the video are all left-handed.

 

[DaveC426913]

Did you notice that the threads in the video are all left-handed.

Heh. So they are.

But many, many videos these days are horizontally flipped. This might have been flipped before adding the text annotations.

Or it was just a bad 3D CG job.

(Aside: I often wonder why so many videos these days are flipped. My best theory is that it is an expedient attempt by plagiarists to discourage roving pattern recognition software from tracking them down and hitting them with C&D orders. It may also be a cheap way of obfuscating corporate logos - for which corps would also probably try to strong arm people into taking them down.)

 

[russ_watters]

Construction jobs are all about getting done in minimum time. Whining to your foreman ("waah, the bolts are too long!") is seen as a weakness. Bump in the road? Figure it out and get it done...

Engineer: Just do it like I designed it!
https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

....not that the engineer didn't screw up a bunch there too.

 

[Baluncore]

Heh. So they are.

I subconsciously sense thread hand. I feel somehow uneasy in the presence of a LH thread, or a reflected diagram of DNA.

There are square "bevelled washers" that are tapered, or shaped like a wedge. They are used only as the first washer, when bolting to the tapered flange of an RSJ or channel, where the fastener would be deformed if a flat washer was used.

RSJs and channels now come with parallel flanges, which is great. When Australia changed from imperial to metric steel sections, the taper angle also changed, which required a different angle bevelled washer. That was a trap for all.

Bevelled washers often have an external corner cut, or a curved face, something that can identify them, and their orientation, while they are in place.

 

[gmax137]

....not that the engineer didn't screw up a bunch there too.

Here's an interesting story, the CitiCorp building in New York. From Veritasium