Live Load vehicle 102 K per axle

[dicksewerrat]

I just had a question about how to do a live load calc. for a pipe with an axle load of 102,000 pounds. Has anyone else seen this size load? The project is in CA. Maybe to take into account earthquake? Seems like a very heavy vehicle. This wa not an aiport but I-5.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Ron]

there's a typo somewhere! I5 wasn't designed for those loads (and neither was any other interstate highway). I've analyzed pavements for a variety of oddball loadings...the space shuttle, trident missiles, aircraft, etc...this one is out of whack.

To answer your question, I would use elastic layer analysis to get the stresses on the top of the pipe.

 

[msquared48]

Ask some probing questions. Find out what, if anything as Ron said, is generating this load.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[SpecialEddie]

I don't have an answer for you off the top of my head, but for buried structures under the AASHTO code, you can ignore live loads for fill 8 feet deep and greater. You can also take an increasing reduction for fill 2 feet to 8 feet deep. Maybe based on the depth of the pipe below grade, you can take a reduction in the live load. Maybe research this part of the AASHTO code and see if you can apply the same theory and logic to the buried pipe. I know that buried structures are different from underground utilities - but loads are loads - seismic, live, or otherwise; and a steel pipe doesn't know it's not a concrete culvert, and vice versa. All the pipe (or whatever is down there) feels is the effects of the live load above. So I'm guessing that the AASHTO buried structure analysis can be extended to underground pipes, if it hasn't already been documented in some other form. But I could be totally wrong, it wouldn't be the first time. Once again, just thinking out loud...

I would verify the loads and axle configuration (I seriously doubt that 102K is supported by a single axle). Current design loads for roads and bridges are for 16K axle loads. There are various other "permit" and military vehicle load that can be accounted for, but my guess that 102K axle load vehicle would not even be allowed to get a permit for use on any interstate highway (I am not familiar with I5). So as the others have suggested the first step is to verify the load, as it appears to be way above and beyond any design criteria for typical bridge and pavement design.

 

[hokie66]

Maybe it's one of these...I know, it won't fit on the roadway.

http://radio-weblogs.com/0105910/2004/06/21.html

 

[Ron]

hokie66..actually, it would fit on the roadway, but not much else would go along with it. Wouldn't be much good for weaving in and out of rush hour, but then why weave when you can flatten. Cool truck!

 

[crossframe]

A supplement to SpecialEddie's first sentence: The effect of live load may be neglected when the depth of fill is more than 8 feet and exceeds the span length. (AASHTO 6.4.2 / AASHTO LRFD 3.6.1.2.6)

This may not apply to the "pipe" in question, but that second part can be important sometimes.

 

[DTGT2002]

A fully dressed (read all counterweights and jib accessories) 200-Ton Truck Crane can have an axle weight of nearly 50,000lbs, with outrigger loads of nearly 200,000lbs.

So a heavier (higher capacity) hydro crane could concievably reach the axle loads you are being relayed.

For normal travel, many parts and pieces are shipped on supporting rigs and secondary axles are employed, but when it is all rigged up, it is heavy with two axle groups.

So it would seem the scenario is possible, but it should surely be possible to find a more manageable construction plan.

When working with the 200 ton crane, the crane drove to its setup location stripped bare for highway/street travel and was assembled my a "helper crane" to get rigged for the big pick.

If the load is what it is, this may not relate, but loads of that magnitude are not out of the realm of possibility for fairly standard construction equipment (200 ton is not all that big cranewise - still half your axle load).


Daniel

 

[PEinc]

I worked on the design of a temporary truss bridge for a Cat 777B off-road dump truck that had 2 axles and weighed 324,000 pounds. So, 102,000 pounds is not impossible and probably not incorrect. See attached photo of the loaded truck.

www.PeirceEngineering.com

 

[dicksewerrat]

Thanks to all. I think they are way too conservative. This was a request from CAL TRANS. I think they know they are out of line.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com