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Washer plate fixing on steel base plate

Washer plate fixing on steel base plate

Hello fellow engineers. We had to design a bracket for a unitized curtain wall for a project in Paris, France (please see attached file). To allow for adjustments during installation the base plate has 2 big slotted holes. Therefore we had to use steel washers (plate 8 mm thk) for the anchors' installation. Since welding the washer to the base plate is not an option (don'task) we decided that the easiest solution is to fix the each washer using two grooved pins with round head(5 mm diameter). But is it the best? The supplier for the grooved pins cannot guarantee the single shear strenght for a pin (just the double shear streght) so they recommended a test.
Are there any better solutions (from a design point of view and installation also) that you can think of? Any feedback would be greatly appreciated.
Pardon my English.

RE: Washer plate fixing on steel base plate

Seems like there are several ways to cut down on the number of separate pieces that have to be made.

How many of these connections do you have to install?

RE: Washer plate fixing on steel base plate

There are a lot. Definitely in the hundreds. Fabrication of the steel parts is not an issue. The fixing of the washers on the base plate is problematic and it's essential we find the best solution. Any thoughts, suggestions or other options (than grooved pins) we might use? Thanks for the answer.

RE: Washer plate fixing on steel base plate

That seems to be an awful detail if you expect to transmit any shear or lateral loading. And, the tolerances in anchor bolt (A.B.) placement are pretty large, +/- 30mm btwn. and 160-170mm setback. Is this in the planning and design phase, or is it already built and now you are trying to figure out what to do with it, to make it work? Since you haven’t given us any of the important design details, we are left to guess at what you need. Remember, we can’t see it from here, and don’t know what you are really trying to accomplish. What are the loads and their directions? I can’t resist asking, why can’t you weld the washer pl. down? They gave you a crappy condition and then tell you you can’t use the most practical way to fix it. Even if that involves a little protective welding enclosure of some sort and a portable exhaust system, which you move from base pl. to base pl. It looks like you are using expansion bolts for the A.B’s. Why note drill std. holes in the base pls., locate and adjust the base pl. as needed, then use it as a template through the std. holes to mark the concrete or even drill directly through the base pl. holes to drill the holes in the concrete? Then set the A.B’s. and use std. washers. You could use epoxied A.B’s.

RE: Washer plate fixing on steel base plate

You're right. I should've given more details regarding loads.
1) So there are a vertical load (gravitational, from the weight of the curtain wall, less than 5 kN) and a lateral load (wind suction aprox 16 kN - see attachement) with no seismic load. The fixing of the washer plates is important to make sure all the lateral load is transfered to the expansion anchors;
2) The tolerances in the base plate of +/- 35 mm are required because those are the tolerances of the concrete structure specified in the french standards; so the bracket has to be able to cover those diferences; the anchor bolt would be drilled/installed first than the base plate position would be adjusted accordingly so the CW's position remains the same. Finally the base plate will be permanently fixed using the washer and tightening the anchor bolt;
3) This is still the design phase, althought a prototype was already fabricated and should be installed next week (the schedule is all messed up). We're trying to find a better solution if any before full fabrication begins;
4) Welding is not an option for "money" reasons (the company i work for -not french- doesn't have and doesn't want to hire a welder authorized to work on site in France - more than that i do not know); so no welding on site;
What I am trying to accomplish is to find the best option (design and installation wise) of fixing the washer plate to the base plate mechanically.
Thanks and sorry for any spelling mistakes.

RE: Washer plate fixing on steel base plate

I have designed similar connections for projects in North America.

What I have seen before is your part 1 is notched so there are "teeth" in the "washer" area of part 1. The groove lines for the teeth run parallel to your slab edge.

The washers also have similar teeth on one side. then, when installing, they can plumb their line and clamp down. the teeth fit together, tighten the nut, and you are fixed in all directions.

Aussi, votre anglais nes pas mal!

RE: Washer plate fixing on steel base plate

So the 6mm/(1/4") sole plate is being clamped against an as-cast pocket in a concrete wall ? Will Any finishing or special work done to create a faying surface smoother and flatter than typical concrete flat work?
The clamping is being done by an M12 wedge anchor bearing on an 8 mm / (5/16") thick plate/washer, that if perfectly aligned will leave the ends of the slot a wee bit open?
And upon final alignment someone will be asked to drill, and maybe even try to ream a 5 mm Ø hole into the 6 mm thick plate backed by concrete?

As others said, I'd be more inclined to rely on some epoxy "chocking" in the oval holes in Item 1.

RE: Washer plate fixing on steel base plate

Why install the bolts first? If you install them as you go, you can add a closure under the washer, same size as the slotted hole in the base plate.

RE: Washer plate fixing on steel base plate

I've got lots of connections in Belgium and north of France in the welding world. Don't hesitate to ask if you need welding related assistance for your work in Paris. Welding would be by far the most economical solution.

RE: Washer plate fixing on steel base plate

Yes, we've considered the option (with the "teeth"). It was deemed too complicated from a fabrication standpoint. Also my french is worse than my english (i'm not french). Thanks.

Indeed filling the holes with epoxy resin or some hybrid mortar seems like the best option; i should've thought of that; also good observation on the washer size; if we use epoxy to fill the hole, the washer should definetly cover the hole completely (in all possible cases). I'll propose the option to the PM.

The reasoning behind the solution was to install the anchors first at the same aproximate position relative to the concrete edge and then align the brackets (and in so keeping the CW position constant regardless of the concrete) using the slotted holes; this way we thought the installation would go faster instead of measuring the exact position required for each bracket.

Appreciate it. Unfortunately it's not up to me. It's the project manager's decision and he's a bit of an [curse word].

Thanks everyone for the feedback.

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