Design of Baffle Wall inside of an Inlet 3

[oengineer]

I seeking information on designing a baffle wall inside of an inlet.

My goal is to determine the required wall thickness and reinforcement for the baffle. My design intent is for the baffle wall to be a reinforced concrete wall.

Water needs to be able to go through the baffle wall, so an opening and sluice gate are required as well for the baffle wall.

Please see attachment for image of the preliminary configuration of the wall inside the inlet:

https://files.engineering.com/getfi...9201-2e340198f2db&file=baffle_wall_detail.pdf

Comments/suggestion are appreciated.

 

[r13]

Yes, both, if you can explain. Thanks.

 

[oengineer]

Yes, both, if you can explain. Thanks.

WSE = Water Surface Elevation (WSE) means the height, in relation to mean sea level (existing grade in case of Zone AO), of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.

I used the throat elevation as the highest point for my water head elevation when calculating my hydrostatic loads, since it was several feet higher than the WSE. Based on JoelTXCive's comments, this should be a pretty conservative design assumption.

 

[r13]

All right then. I am very bad on abbreviations, it always make me nervous when guess. How about FEL (free water elevation), or MWEL (maximum water elevation) Just to make sure it is the maximum expected water elevation then.

 

[oengineer]

All right then. I am very bad on abbreviations, it always make me nervous when guess. How about FEL (free water elevation), or MWEL (maximum water elevation) Just to make sure it is the maximum expected water elevation then.

The section detail provided in the post was put together by the civil engineer. I did not set the abbreviations.

 

[JoelTXCive]

Oengineer. Yes, your water depth is conservative, but not crazy based on your geometry.

It doesn't really matter what the throat elevation is. Once water gets to the top of the baffle wall, it will flow over. Then you will have the same head on both sides. The throat could be 100ft up, and it wouldn't change the pressure on the wall. As long as water is on both sides, then it nets out to zero.

I'm with you on the 10" thick. I was just throwing out 12" in case you had super long anchors (i don't think this will be the case for a 24" gate.)

For gate structures like this, often times constructibility issues govern the design. You want to make sure there is room to get the gate in and out. Also, try and be nice to the engineer that has to replace or modify it 15 years down the road. Leave them some room to work.

 

[JoelTXCive]

I forgot. Do you have a preliminary gate schematic?

If not, you might want to have the contractor submit gate drawings prior to construction for your review. That way you can review the gate geometry and make sure it fits. Or put a comment that the contractor is responsible for making sure the gate works with your geometry.

 

[r13]

That's okay, as long as the symbol indicating water is there, people will get it (not me though . Another thing to keep in mind is the stainless steel for the gate framing should be ASTM 316, not 304, for better corrosion resistance.

 

[oengineer]

I forgot. Do you have a preliminary gate schematic?

If not, you might want to have the contractor submit gate drawings prior to construction for your review. That way you can review the gate geometry and make sure it fits. Or put a comment that the contractor is responsible for making sure the gate works with your geometry.

I do not have a preliminary gate schematic. To be honest, I am not sure what that is. All I really have is the sketch contained in the link at the beginning of this post.

As of this point I am in the design phase, so I do not believe a contractor has been selected yet. The civil engineer has not made me aware if a contractor has been selected.

Would anyone please explain what does "MOC cast iron" mean? A vendor for a sluice gate that I reached out to mentioned this phrase.

 

[oengineer]

Another thing to keep in mind is the stainless steel for the gate framing should be ASTM 316, not 304, for better corrosion resistance.

Thank you for this advice.

 

[JoelTXCive]

I'm not sure what the "MOC" stands for.... "Material of Construction?"

These gates are often cast iron like a storm sewer cap. They can also be stainless steel (which is more expensive).

I think the cast iron is more common. Let me look through my files. I probably have some example drawings from Rodney Hunt (parent company is called Dash) or Waterman. They make a lot of these gates.

 

[JoelTXCive]

I apologize. I do not have any 24" diameter sluice gate drawings. I have some big square ones (10' x 10' or 12' x 12'), but I don't think that will help you.

Go to Rodney Hunts website and download their catalog:

https://www.rodneyhunt.com/cast-iron-sluice-gates/

Even though you do not know the brand or model of gate going in, the catalog has lots of photos and some geometry in it. On the projects I have worked on, I often do not know the make or model of gate going in on the front end; or the gate will get changed during the bidding process.

It's best to have your baffle wall (and junction box/manhole) setup in a way that will fit most gates. This means room to the left and right of the gate, along with above & below it for mounting a variety of gate frames.

 

[r13]

I think you've already done a lot, including researches, up to this point. It should be a good time to talk to your civil engineer, I guess he is leading the effort, and can clear some of your questions and concerns. I believe this "regulator" is located in a flow channel, are there other functions/concerns beside control the pipe flow? Try to understand the project as much as you can get, some concerns may not have direct relevance to your task, but may be helpful down the road.

 

[oengineer]

I apologize. I do not have any 24" diameter sluice gate drawings. I have some big square ones (10' x 10' or 12' x 12'), but I don't think that will help you.

Go to Rodney Hunts website and download their catalog:

https://www.rodneyhunt.com/cast-iron-sluice-gates/

Even though you do not know the brand or model of gate going in, the catalog has lots of photos and some geometry in it. On the projects I have worked on, I often do not know the make or model of gate going in on the front end; or the gate will get changed during the bidding process.

It's best to have your baffle wall (and junction box/manhole) setup in a way that will fit most gates. This means room to the left and right of the gate, along with above & below it for mounting a variety of gate frames.

This is the vendor that I reach out to. Good to see that I am on the right path. I am new to baffle wall design.

Based on the picture that I provided, would it be correct to assume a manual operator for the sluice gate?

If so, what would be a reasonable top elevation level where the operator will be located?

I think you've already done a lot, including researches, up to this point. It should be a good time to talk to your civil engineer, I guess he is leading the effort, and can clear some of your questions and concerns. I believe this "regulator" is located in a flow channel, are there other functions/concerns beside control the pipe flow? Try to understand the project as much as you can get, some concerns may not have direct relevance to your task, but may be helpful down the road.

Thank you.

I am wondering if i should ask the civil engineer the following questions or research it 1st:

[ul]
[li]Manual operated sluice gate?[/li]

[li]Top elevation level where the operator will be located?[/li]
[/ul]

 

[r13]

Talk to him, he's the boss, and its his call. Your job is to design the wall, and make sure it can easily accommodate the gate framing requirement (framing stud embedment). Get the type and size of the gate, which may affect your opening.

[ADD] If the structure is in a flow channel, what is the maximum flood elevation, and how the operator gets to it?

 

[JStephen]

Waterman is another supplier of sluice gates.

 

[oengineer]

The vendor has recommended us to use a "self-contained" sluice gate for our application.

The vendor also mentioned "seated" and "unseated" head of water acting on the sluice gate.

Could anyone please explain what that actually means in relation to sluice gates?

 

[r13]

See the sketches below. The self-contained gate has a closed frame, while un-contained gate does not have the header. The seated head is the operating head pushing the gate into the wall; the un-seated head is the operating head pushing the gate out of the wall. You shall let your civil engineer to provide these operating heads (simply the maximum backup water on each side of the wall while the gate is closed - one side with full head and the other side is empty as shown).

 

[oengineer]

See the sketches below. The self-contained gate has a closed frame, while un-contained gate does not have the header. The seated head is the operating head pushing the gate into the wall; the un-seated head is the operating head pushing the gate out of the wall. You shall let your civil engineer to provide these operating heads (simply the maximum backup water on each side of the wall while the gate is closed - one side with full head and the other side is empty as shown).

Thank you for the explanation.

How about what "seated" and "unseated" head of water acting on the sluice gate means?

[ADD] - Sorry, I misread your explanation. You explained both concepts. Thank you again.

 

[r13]

These the contractors terminology. See the sketch, I guess the left side is "seated head" situation (on-seating head), and the right hand side is "unseated head" (off-seating head). You can verify with the supplier. I general, I think you shall install the gate on the upstream side of the wall, and let the wall facing incoming flow, because the downstream side is likely to have minimal water remain,or empty while gate is closed, but the upstream side will be filled with backup water.

Pressure Head Push gate into wall - Seated Head (On-seating head)
Pressure Head Push gate out of wall - Unseated Head (Off-seating head)

 

[JoelTXCive]

There is usually a larger seated head capacity than an unseating head capacity.

For a seating head, your anchor bolts aren't doing much work. They carry the gate's self weight in shear only. The water pressure applied to the gate is transferred to the concrete through bearing pressure applied by the frame.

For an unseating head, your anchor bolts still carry the self weight, but are now in tension and working hard. The concrete breakout, tearout, pryout etc. limit states now apply.

It's easy to check these items though. You can come up with a shear and tension force per anchor bolt, and then plug into the free hilti or simpson software.

Most people make the assumption that all the shear loads are carried uniformly by all the anchors. Take the self weight of the gate and divide by the number of anchors.

For the tension load, Rodney Hunt (gate manufacturer) uses the water pressure at the gate centerline and applies it to the entire gate. For small gate like yours though, you can just take the water pressure at the bottom (flowline) since it's easier to calculate.