Building A Bridge

[Toiyabe]

Koop,

That photo scares the heck out of me. You need to have that bridge evaluated by a P.E. with regards to its new setting. You need to have the foundations designed by a P.E. You need to have the bridge periodically inspected by a certified bridge inspector.

If there isn't a law in Virginia that forces you to do those things, there should be. That is a serious bridge.

Don't cut into your saftey factors. That's always a bad idea, but in the case of this bridge it is a incredibly bad idea.

Nothing personal, but I think VDOT was crazy to sell that bridge to a private individual for anything other than scrap.

 

[Renze]

Koop,
That photo scares the heck out of me. You need to have that bridge evaluated by a P.E. with regards to its new setting. You need to have the foundations designed by a P.E. You need to have the bridge periodically inspected by a certified bridge inspector.

If there isn't a law in Virginia that forces you to do those things, there should be. That is a serious bridge.


Nothing personal, but I think VDOT was crazy to sell that bridge to a private individual for anything other than scrap.

You SHOULD blah, you SHOULD blah, but there isnt any law forcing you to do so... And the government shouldnt.....

I'm just glad it's not you who makes laws... It would make any commercial undertaking impossible.

In my business, the trailer business, there are tons of laws of you should this and you shouldnt... But if you put something plain stupid on the road even though it is approved, approved or not if somebody dies the lawyers still know how to find you...

So if all those rules and laws still have loopholes that allow folks to put dangerous and stupid stuff on the road one one hand, yet cause high cost for the manufacturer, and still dont take away the product responsibility from the manufacturer to the institution that checks if these loopholed laws are carried out, it doesnt help responsible enterprise at all...



why would he have an engineer to calculate the foundation ? The worst thing that could happen is the bridge sinking a couple of inches deeper into the sand..
Even if the bridge itself would fail, sinking a few feet down into the river bead, the thrill wouldnt be even close to the roller coaster ride we have us kids make in the amusement park....

 

[Toiyabe]

You SHOULD blah, you SHOULD blah, but there isnt any law forcing you to do so... And the government shouldnt.....

I don't know Virginia law, so I don't know what the requirements are in this case. I do know that if it were a bridge that carried a public road, it would need to be designed by a PE and inspected periodically by a certified bridge inspector.

I'm just glad it's not you who makes laws... It would make any commercial undertaking impossible.

Just like building codes make it impossible to build buildings. I wonder where all these buildings came from then?

In my business, the trailer business, there are tons of laws of you should this and you shouldnt... But if you put something plain stupid on the road even though it is approved, approved or not if somebody dies the lawyers still know how to find you...

Yup, if you do something stupid that causes someone's death you'll be seeing the insides of a courtroom.

So if all those rules and laws still have loopholes that allow folks to put dangerous and stupid stuff on the road one one hand, yet cause high cost for the manufacturer, and still dont take away the product responsibility from the manufacturer to the institution that checks if these loopholed laws are carried out, it doesnt help responsible enterprise at all...

Maybe because some people think that preventing deaths is a good thing? Sure you can't cover everything with laws, but some laws to keep people from doing really stupid things might be a good thing. For the rest, there is civil liability, as you said.

Also, these basic laws do help responsible enterprises. They keep the shady fly-by-night enterprises from undercutting them with unsafe products and then folding up and disappearing when things go wrong. Maybe we'd still be making trailer tires in the US if there was enforcement of some sort of basic standards.

why would he have an engineer to calculate the foundation ? The worst thing that could happen is the bridge sinking a couple of inches deeper into the sand..
Even if the bridge itself would fail, sinking a few feet down into the river bead, the thrill wouldnt be even close to the roller coaster ride we have us kids make in the amusement park....

You are making gross assumptions about the site. What do you know about the elevation of the bridge? What do you know about the potential for scour, or uneven settlement? Can you imagine what might happen if one corner of a 50 ton structure settles faster than the other three corners, especially if it is only rated for a 7 ton live load? 50 tons is a wild guess from the photo, but note that it came in on an overweight permit.

How do you know that the bridge will fail in a gracefull, ductile manner? Doesn't the fact that it may be highly deteriorated cause you to wonder? I assure you, steel trusses have failed catastrophically with loss of life in the past, and will in the future.

 

[Kendall69]

...I prefer to laugh with Timber, Greyfield and Gotrocks and actually learn something from Renze, D7E, Schmism and Toiyabe

The only person laughing is me. Thinking for one second you can “learn” something about a bridge from people on the internet who haven’t seen the bridge in person, is the funniest thing I have EVER heard of.

..self righteous lecturer

Yep that’s me alright. I tend to give self righteous lectures to, drunks who are about to drive, kids who play with matches, passengers who don’t wear seat belts, people who play Russian Roulette,...and most of to people who don’t want to spend money doing a job right that will endanger people lives.

If you can’t handle the truth...don’t ask the question.

 

[Renze]

No, excess laws dont prevent anything from being built...
It's the mood of the inspector that prevents things from being allowed... the law is all about interpretation. If something is legal, all depends on by who, and how something is interpreted.

I dont know how it works in America, but the great European law, is a lot of smoke and little fire. Stupid, cost adding, unnecessary things are bound in laws, where i see high risks getting a type approval through loopholes, without anyone seem to care.

You are making gross assumptions about the site. What do you know about the elevation of the bridge? What do you know about the potential for scour, or uneven settlement? Can you imagine what might happen if one corner of a 50 ton structure settles faster than the other three corners, especially if it is only rated for a 7 ton live load? 50 tons is a wild guess from the photo, but note that it came in on an overweight permit.

How do you know that the bridge will fail in a gracefull, ductile manner? Doesn't the fact that it may be highly deteriorated cause you to wonder? I assure you, steel trusses have failed catastrophically with loss of life in the past, and will in the future.

May i remind you that, since both of us share the same amount of knowledge about the bridge site (which means nothing), we both are purely assuming, you just as much as i am ??

Also, these basic laws do help responsible enterprises. They keep the shady fly-by-night enterprises from undercutting them with unsafe products and then folding up and disappearing when things go wrong. Maybe we'd still be making trailer tires in the US if there was enforcement of some sort of basic standards.

You do have a good point: When there are loopholes in the road traffic laws, there are also loopholes in the law to get away with legal liability and product responsibility, like manufacturers that stuff the market with dodgy stuff and are already gone when the **** hits the fan...

For me personally, business is like this: Build trailers for our customers like you'd like to use one yourself (safe, solid, responsible)
For the rest, if necessary, use existing loopholes in the law to get your safe, solid, responsible product on the road. After all, we work to earn a mouthfull of bread...





About that bridge, it somehow remembers me of the Bailey bridges the allies used in WW2... if it is a Bailey, it should take a Sherman tank or 2....

 

[bucmeister]

Koop,

You mentioned a low water bridge now being used, which would cause me to speculate that this bridge is not crossing a 90' deep ravine. I, for one, would like to hear about the crossing. Is this bridge going to span the same distance that it did originally? Can the new supports be set so that the free-span length is reduced? Is it possible to place a center span support pier?

For me personally, the circumstances of the crossing would be a factor in what I would risk. If the span were as long as original but only 5' off the stream bottom I would feel different about it compared to a 15' deep stream. Not that you would want to lose the bridge under any circumstances, but a 5' collapse would be less likely to hurt someone when compared to a 15' collapse. Around here we have a lot a 2-lane state highways with the bridges rated at 52,*** lbs (not sure why that is the prevailing figure) and they are constantly crossed by log and grain trucks weighing in excess of 80,000 lbs year in and year out. This practice is well know by the state regualtors and no effort is made to stop it. The limits seem to be more of a CYA effort by the state because the state DOT itself routinely moves loads exceeding the posted limits across these bridges.

 

[sandman2234]

Adding another Assumption to the lengthy list:
Changing the span would seem like a good idea, but in the case of engineered components, this is not always a good idea. Where the load is transfered to the ground is often a build in design itself and changing that can cause catastrophic results. I know if this were a prestressed beam it would make a major difference, and can see where steel bridges could matter, and by the way, I am no engineer.
David from jax

 

[SkunkWerX]

Forget Laws and Engineers, for just a moment, and think about this:

Insurance.
My brother in law who is in the insurance industry (Commercial stuff) says that everything is moot, if it is "Uninsurable".

If you plan to insure yourself, at that property, then the Insurance Company is going to dictate a lot of what you need to do. You can bet they will want a full fledged Engineering evaluation of the bridge, including proposed foundation.

It is highyl unlikely you could even get any liability insurance for the property at all, with the bridge excluded from the policy, so, you end up being 100% uninsured, which means you are open for any kind of lawsuit that comes down the pike.

If you are NOT planning to insure yourself, at all, then heck, post a sign that says "Weight Limit 10 lbs" , it won't protect you in the least.


In the courtroom:

"Mr. BridgeOwner, did ever contemplate the consequences of this bridge?"

-If you answer "NO" it's grounds for Negligence

-If you answer "YES" and still did nothing, then it's grounds for WillFull Negligence.

Either way you will be found Negligent.


If you aren't worried about losing ALL of your assets, the 10 or so years in jail should be considered. Then, when you get out of jail, you can sit in court during the Civil LawSuit.

My recommendation: Forget the Loads it will handle for now, get yourself a savvy Insurance person, and get it Insured. By virtue of having the insurance, you will end up with the proper safety inspections and documentation.

 

[Blk88GT]

I'm sorry, but this thread is hilarious.

I have nothing of value to add, other than I'd love to have a bridge and I think it's awesome you're going to use that one.

I'd use it and never look back.

 

[schmism]

In the courtroom:

"Mr. BridgeOwner, did ever contemplate the consequences of this bridge?"

IS that like "if a tree falls in the woods, does it make a sound?"

"i dont understand the question, can you please rephrase" would be the correct answer...

9. A Coal Mine operates a NFPA Class 1, Division 2 Hazardous Area.

Before i was in trusses i worked for Killark designing lighting for hazardous locations. I acutally know what a Class 1 Div 2 enviroment is!

 

[KentT]

My recommendation: Forget the Loads it will handle for now, get yourself a savvy Insurance person, and get it Insured. By virtue of having the insurance, you will end up with the proper safety inspections and documentation.

Why not just jump straight to the lawyer and get his advice -- bypassing another "potential middleman" of the insurance company -- since fear of litigation is your motive?

I'm glad a culvert met my needs, but I guess I should be so concerned that someone will drive off the edge of the driveway crossing it where it's about 6 feet above ground level and doesn't have a guardrail, that I should just require everyone to park on the road and hike in...

Geez.........

 

[sandman2234]

Between the lawyers and the engineers and the insurance people and us, I know why he has been using a low water crossing!
David from jax

 

[pat32rf]

Up here in Ontario the Min. of Nat Resources would soon put an end to that "low water crossing". They would also demand a work permit before the bridge was installed.

 

[koop]

Koop,


Nothing personal, but I think VDOT was crazy to sell that bridge to a private individual for anything other than scrap.

Why?
This bridge was in use up to the day it was moved.
Less than a year ago, VDOT had the bridge inspected and it was given a 7 ton rating in its current condition. One concern mentioned in the report was the condition of the crumbling stone abutments. The report also stated the average traffic volume was 300 - 400 cars per day.

So I ask why is this bridge only good for scrap? It will be repaired, painted and set on brand new abutments. Not to mention, on a heavy traffic day, there might be 6 trips across.

I would like to help clear up some of the assumptions being made.

The bridge weighs approximately 68000 lbs.

Because this bridge spans bank to bank, we should not need a permit, although we are waiting for this to be verified by the appropriate agencies.

The bridge spans the head waters of a small river with average depth of 12" - 18". The bottom of the bridge will be set about 6' - 8' above the river to ensure good flow beneath the structure during high water events.

The low water crossing is sufficient at the moment because it is only used a few times a year.

Perhaps the worst assumption to be addressed is from Kendall69. This forum is a great way for me to hear the perspectives of other members, even if I disagree with them. I really appreciate the input from critical thinkers (Toiyabe). I don’t see the value in those who choose to respond to my questions by assuming I am an idiot who wants to cut corners to hurt my family and friends and that the forum is a useless tool with which to gain information to assist in making a sound decision. You think that in asking my question I am analogous to a drunk driver etc, shows you think the worse of people and Tractorbynet members and that is a shame.

 

[Toiyabe]

I think that VDOT should have scrapped that bridge before letting a private individual get a hold of it for liability concerns. It would be a shame as it is a very nice looking bridge, but it has a great potential to cause harm if used inappropriately.

My wild guess of 50 tons was wrong. Still, the fact that it weighs 34 tons but is only rated for a live load of 7 tons should clue you in to the fact that you are dealing with a structure on a different scale than most people are used to.

There is something sometimes called the "square-cube law". It states that the strength of a structure increases as the square of its length (cross-sectional area) whereas the the weight increases by the cube of the length (volume). So as things get bigger, they get heavier much faster then they get stronger. It isn't strictly true, but is good for mental approximations. The upshot is that big structures don't behave like scale models of themselves, although people often think that way. That way of thinking can lead to big trouble.

This is a very difficult thread to be involved in. I have an ethical requirement to urge you to seek professional advice while not giving you anything that could be seen as professional advice.

 

[Renze]

I have an ethical requirement to urge you to seek professional advice

Some hilarious replies were already made, but this one just tops it









... just kidding.
btw, good point about the square-cube law. Translating it into everyday language, it means that when doubling the span of the beam, the bearing capacity reduces to 1/3 or am i having my maths wrong ??


Do you guys in America have the same standardised hot rolled steel profiles as we have in Europe ?? If you can give me the steel profiles and steel type, i can put it into my construction program... But i dont know what loads should be calculated for bridges as i usually just calculate trailer frames, for which are no prescribed load situations, just common sense.

 

[koop]

Renze,

You have seen the picture, I can give you the dimension of every piece of steel you see. Just let me know. I would love to see what your program comes up with.

It would appear I need to reassure everyone that if your program says 40 ton weight limit that I am not going to invite every tandem axle dump truck with 4 pony axles and 23 tons of gravel to come test your results. LOL

 

[Toiyabe]

The square cube law would state that if you double the scale of a structure, the weight would increase by a factor of 8 (2^3), while the cross-sectional area of the members would increase by a factor of 4 (2^2). Cross-sectional area is proportional to strength for members in pure tension, for members in bending or compression it is more complicated. The actual change in live load carrying capacity would vary based on the ratio of dead load to total load.

The square cube law isn't something to be used in actual calculations. I only brought it up as one reason why extrapolating from experiance with small structures (such as trailers) to large structures is dangerous.

Unless you specify your steel shapes in inches of depth and pounds per foot of weight, I doubt the hot rolled sections are the same in the US as in Europe. Steel grades are also different. Based on the photo, I doubt that it is made from current standard sections.

Computer programs are garbage in garbage out. Unless you know how it works, you are not likely to get the right answer. And without experiance in the field, you won't know what the right answer should look like.