Need some engineering help

[Sono]

We have a bridge that is the only access to and from our house ( 100% our responsibility ) it is a 6' diameter concrete pipe with 6" wall thickness. From what I see there is what looks like 3/16" wire reinforcement in the exposed weathered ends. Then the concrete slab poured over it is 6" thick at the expansion joint in the center above the pipe and gets thicker as it goes out towards the street and our driveway. There is no information on this bridge at all ( apparently wasn't any codes at the time as this was farmland at one time ) I am trying to find out what the weight limit is of this bridge as I want to clean up the creek and our little "pond" to reline the banks with stone/rock where the water is washing out and eroding the soil into our yard due to the current during downpours coming through that culvert under the bridge.

Anyone have any idea what it will support as far as weight since I want to get a couple dump trucks of stone and have dumped this side of the bridge close to where I will be needing it? As soon as all the poison ivy/sumac and all the honeysuckle goes dormant I need to get in there and clear it out, remove a few dead trees as well, drive some steel reinforcement rods/pipes to help hold the rocks in place til they settle, maybe hog wire as well?

Thanks for any help

** The concrete at the expansion joint is 12" thick from the inside edge of the pipe to the surface of the bridge**

 

[drssg]

I wouldn't count this as engineering advice, but I have a similar size bridge over a similar creek. I've had plenty of gravel trucks delivering 20-25 tons of stone, and it hasn't shown a hint of an issue. If you have smaller trucks delivering maybe 10-15 tons per load, I would think it would be fine. (But don't send me the bill if I'm wrong. )

FWIW, mine is a straight metal pipe that is covered with 4-6" stone, then a finer layer on top. I don't know whether that design is stronger or weaker than yours.

 

[2LaneCruzer]

I wonder if a couple of 16' 2X12 wouldn't help distribute the weight of the truck as it passes over....???

 

[Streetcar]

You have worse case design wise. Joint in pavement and concrete on pipe lead to point loads. Pipes are designed to be buried

 

[Streetcar]

In real world I have seen similar pipe many times. After first dump truck goes over pipe. Check for cracks near top of pipe. You should be fine with standard dump truck. To protect pipe you could dump gravel on concrete 6 “ would distribute street from additional trucks

 

[Egon]

One option would be some vertical support posts inside the culvert and underneath the tire footprint of the vehicles. They do not have to be fancy; just four or so 6x6 wedged into position in the pipe.

Note: this is not engineered design advice.

 

[Sono]

My thought as well as the slabs don't meet and wont at that joint unless the pipe busts....lol
A bobcat moving sand has passed over it many times with the pool install but they wouldn't drive the truck/loaded trailer over it....

 

[Sono]

And don't worry, Im not holding anyone accountable LOL
Im just trying to figure out the weight limit or so...……… I really don't like it, the culvert is too small for one as when it rains the water backs up and sometimes floods the yard and over the bridge as well... the other side stays lower as its just too small of a bottleneck there. Whoever did it should have put 2 in or should have done it correctly with 2 concrete piers on each side with Iron supports and a slab over that to be proper. If it ever needs to be done or if we do any land improvements with the creek area.

 

[Mendonsy]

Another thing you could do is get some steel plate and lay it over the bridge where the dump truck tires will run to spread out the loading. A 4' x 8' sheet of 1/2" or 3/4" steel cut in half would get you two 2' x 8' plates.

 

[ruffdog]

How wide is the bridge? I'm just wondering how close to the end of the tube the weight will be as it makes a difference on supporting the weight.

 

[Cat_Driver]

Liability. Do everything by the book. Don't get advice here get it from a licensed Engineer.

 

[otlski]

I would try to couple the top slabs to the pipe with pourable grout. It looks like there is considerable space between the two and as mentioned above, is a likely place to see point loads. Use a foam sheet to preserve the expansion joint.

 

[Big Barn]

Liability. Do everything by the book. Don't get advice here get it from a licensed Engineer.

That would be my opinion also. Smaller trucks wouldn’t make much difference as bridge loads depend on the number of axles in addition to total weight.

 

[BoylermanCT]

Do you have fire hydrants near you? If not, if you have a fire, the fire dept will show up with a 50,000lb water tanker. Would be good to know if your bridge can support the weight. My fire dept just assisted the next town over with a house fire this weekend and a total of 27 tanker loads were delivered to fight the fire.

 

[4570Man]

Liability. Do everything by the book. Don't get advice here get it from a licensed Engineer.

How would am engineer go about a problem like this? There isn’t enough known about the structure to draw a valid conclusion.

 

[Big Barn]

How would am engineer go about a problem like this? There isn’t enough known about the structure to draw a valid conclusion.

He would say rip it out of course.

 

[4570Man]

That probably exactly what they would say.

 

[Tractor Seabee]

Do you have fire hydrants near you? If not, if you have a fire, the fire dept will show up with a 50,000lb water tanker. Would be good to know if your bridge can support the weight. My fire dept just assisted the next town over with a house fire this weekend and a total of 27 tanker loads were delivered to fight the fire.

Fire departments around here are requiring engineer load data on obvious owner non-permitted bridges or visually defective bridges. No Data no fire service, they will not cross the bridge.

Ron

 

[Tractor Seabee]

That probably exactly what they would say.

I agree, those round culverts, like has been said, are designed to be buried under engineered fill. Hard to tell from the picture but it appears the slab is in contact with the culvert. Probably no reinforcing in the slab to make it self supporting of the loads implied to be applied. If the slabs have no obvious faults you may be OK. If i has been there this long surely truck loads have been applied in the past. get your gravel in the smallest dump trucks they have not over 10 ton. Then again the truck driver is in the drivers seat. He has a liability issue staring at him.

Ron

 

[dodge man]

I will start and say I am not an engineer but a land surveyor, but I work for an engineering company. Pipe have to be stronger when shallow because as already mentioned point loads from trucks. As you get deeper they can be weaker because the cover spreads the load out, then as the get deeper yet they get stronger again because of the weight of the dirt. The problem I do not know how you can tell the difference looking at the pipe. So it might be the strongest or the weakest.

Let me just say I would be concerned driving fully loaded trucks over it.