required to check adequacy of pier

[zohl]

required to check adequacy of pier and pile cap for barge collision in a very low volume river traffic and no information about barges

 

[phamENG]

Sounds like an impossible exercise in futility. Good luck.

 

[bridgebuster]

AASHTO publishes a guide specification for collision design of highway bridges. It costs $125.00. There's also a section on vessel collision in the AASHTO LRFD specs; it's expensive to buy, nearly $600.00

Try googling "vessel collision design of highway bridges" you can find some free information.

Hit the submit button too fast. Is this for a project in the US? if so, you should be able to get information about the river traffic from the Army Corps of Engineers or The US Coast Guard. The Corps has jurisdiction over all navigable waters in the US. The Coast Guard has jurisdiction over bridge clearances; so they keep records of ship sizes. Otherwise, you could make observations or ask people in the area about the river traffic.

 

[BridgeSmith]

I don't like to be the doom and gloom guy, but unless the pier is massive, and the barges are smaller than what I'm familiar with, it's very possible the only check that will matter is whether the superstructure collapses or not with the loss of the pier.

If there is a possibility of the loss of a span, there's also the aspect of the sight distance to consider. The Sunshine Skyway collapse is a demonstration of this type of danger. Several vehicles went off into the water well after the span collapsed, because they could not see that the span was gone until it was too late to stop. If your situation turns out to be similar, consider the measures outlined in the NTSB Safety Recommendation that resulted from that failure a failure with similar aftermath of the I-40 bridge near Webbers Falls, Oklahoma.

The superstructure is usually all we check related to pier impacts from trains. They can sag several feet, but as long they don't break, they've met the life-safety criterion. AASHTO is moving that direction with the bridge design specs, as well, as the more efficient way to provide life-safety protection. The impact forces are too high for our typical piers to withstand, and they'd have to be way more massive to survive.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[bridgebuster]

Rod - if a bridge has to be protected from collision, it would need something like this, stone filled cells with a timber fender

 

[BridgeSmith]

Rod - if a bridge has to be protected from collision, it would need something like this, stone filled cells with a timber fender

Yeah, that will work, too. If it is deemed necessary to protect the pier, it seems to be a really good solution. Depending on the situation, other options may provide a life-safety level of protection at less expense, if that's all that's required.

That's interesting; thanks for the info. We have no navigable waterways in Wyoming, so I don't really keep up on vessel collision protection...

Rod Smith, P.E., The artist formerly known as HotRod10

 

[bridgebuster]

Rod, this bridge does see some decent sized vessels from time to time, which is why this system was needed. FWIW, in my younger days, I was the resident engineer for the construction of that fender system.

 

[SlideRuleEra]

For barge traffic, dolphins (see photo), traditionally constructed with driven timber piling and used along with timber fenders frequently protect bridge piers from impact. This 376 page publication prepared for the US Navy, "Analysis and Design of Dolphins" likely will include info on ship/barge collisions. (I have not read thru the document to determine that).

Dolphins have a number of uses, protection of piers is just one.

http://www.SlideRuleEra.net

 

[BridgeSmith]

That's cool, Bridgebuster!

As I said, here in Wyoming, we only have to deal with vehicle and train collisions. Under previous versions of the AASHTO spec, it was 400 kips for both - which we thought was ridiculously low for a train impact. The new version has 600 kips for vehicle impact and in the commentary it says "Requirements for train collision load found in previous editions have been removed. Designers are encouraged to consult the AREMA Manual for Railway Engineering or local railroad company guidelines for train collision requirements." Essentially, having no good information on impact loading from a derailed train, AASHTO punted. However, the section on vessel collisions is quite detailed.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[r13]

Linked is part of USACOE design manual that gives barge impact design load. Link

Please note introduction says "This guidance applies to structures whose primary function is hurricane flood protection in the New Orleans area, which includes T, L & I-walls, sluice gates, fronting protection and flood gates. Sector gates and other navigable waterway structures shall have all design criteria approved prior to design."

I think OP wasn't looking for design guidelines, but what to look for - bridge/deck support as mentioned, any other things he shall keep in mind?

 

[jrw501]

You should be able to reasonably determine a design vessel (in addition ACoE and Coast Guard, you may simply find google maps helpful, since they often have images at the crossing, upstream or downstream that show water traffic) and in the absence of one, you may try to find a similar waterway that does have information (to at least give you something to work with).

You'll need the barge make up (i.e. something like a 1 wide x 5 long barge), the barge tow speed for kinetic energy calcs (you may need to make assumptions for the event under consideration, like maybe a runaway situation during a flood event for off-channel piers that vessels can still reach and a more typical vessel speed for piers adjacent to channel that might occur in times of poor visibility), the loaded draft, loaded weight/displacement (empty + cargo capacity), and towboat characteristics (really just the displacement/weight).

You can then check the pier/pile cap/piles for various failure modes due to head-on and side collisions (at half the head-on load) and determine if the pier is adequate, or may need some pier protection/fender system.

 

[BridgeSmith]

Prior to getting carried away, a 400-kip collision force was used.

Previous editions recommended use of an empty barge with a weight of 200 tons, but gave several factors (flow velocity, direction of flow relative to the pier, etc.) to determine the vessel collision load.

The 400 kip impact load was for trucks and trains. They've since bumped the truck impact up to 600 kips and punted on the train impact, deferring to AREMA, which I think mostly recommends assuming the derailed train destroys the pier and wants you to design accordingly.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[phamENG]

TheRick - 200 tons = 400 kips, but that doesn't matter anymore when you leave static loading. These are impact loads, so they have to be able to absorb the energy of the barge. Designing for an arbitrary equivalent static load is just an attempt to make a structure that's big enough and stiff enough to absorb the energy. It's an imprecise way of designing that sort of structure. My preferred method is to determine the max design vessel mass and velocity and use that to determine the max kinetic energy to be absorbed. Then, apply a load to your structure and watch it's deformation behavior and strains. Determine the applied force that will cause the structure to store an equivalent amount of strain energy, and design to that load with an appropriate factor of safety.

Full disclosure: I'm not a bridge engineer, but I've done a handful of piers and mooring facilities for commercial barges and oceangoing vessels.

 

[jrw501]

We've done something similar to what phamENG describes in some cases, I think mostly in design of fender systems. But for evaluating existing piers or designing new ones we just follow the AASHTO Vessel Collision Specs to determine the loads, which can obviously be quite significant depending on the situation (I've looked at a few in the 2000-4000k range).

 

[BridgeSmith]

a 200 ton barge is still 400 kips correct?

Yes, but a weight of 400 kips doesn't equate to a 400 kip impact...

Looks like phamENG said the same thing while I was distracted with something else and didn't get back to my post for awhile.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[bridgebuster]

 

[BridgeSmith]

AASHTO needs to get the college professors out of the code writing process!

Amen, brother!

Rod Smith, P.E., The artist formerly known as HotRod10

 

[BridgeSmith]

I don't have a copy of the AASHTO code prior to the 7th Edition, I couldn't remember everything off the top my head.

I get it. I don't know anything about vessel collisions off the top of my head, since it's not a loading we deal with. We do have all the editions of the AASHTO LRFD spec around here somewhere, as well as several editions of the Standard Specifications.

He's probably just more confused now LOL

Better to be confused than designing based on an incorrect assumption. I don't know what barge impact force should be for design, but I'm fairly sure it's going to be more than 400 kips.



Rod Smith, P.E., The artist formerly known as HotRod10

 

[r13]

zohl,

Are you review someone's design for barge impact on a pier, or to perform field inspection on a pier, for which a recent barge impact has occurred? Different scope has different technical needs.