Type "S" Dump Truck Loading on Bridge

[visitor]

Hi everyone,

I am designing a bridge with a simple span of 80 feet. the AASHTO loading is not a problem and is applied by the Book. The owner wants an type 3 dump truck loading applied also . the "type 3" weighs 33 tons (66000lb) front axle=14kips middle axle=26 kips and 12 feet away from front axle and the rear axle is also 26kips and 4 feet away from the middle axle.

I understand the type 3 truck is one of the FHWA loadings that some states have adopted. You see I really havent dealt with anything but HS trucks.

This might sound somewhat elementry but how do you apply this load?? do you put one truck in the middle like is done with AASHTO HS truck? You see, with an HS truck there is also a lane loading which modles a train of trucks back to back when the span is long enough. but in this case there is no lane loading (and if there is I dont know about it) and the Span is long enough to accomodate at least three or even four trucks with reasonable distance between them. and as you might have observed dump trucks more or less haul in convoys.

PLEASE HELP !

Thank you very much

 

Correctio to title ,
It is a TYPE 3 truck
My apologies

 

[Qshake]

Yes, the question is elementary, but alas a solution is at hand. If you don't want to pull out your old structural analysis text or, God forbid, your statics book, then take out your AISC Standard Specifications and look in the section where the beam formulas are. There is a section on truck loads and positioning for maximum moment on...a simple beam!

I would recommend that you do some more investigation and determine what, if any, lane load exist. As you are probably aware a concentrated load accompanies the lane load. A single for maximum positive moment and two concentrated loads for maximum negative. The latter, of course, you won't need to bother with. The former may be of some interest depending on the values as it may exceed the truck loading. I would try

http://www.fhwa.org

first for some more information.

 

[Ingenuity]

Qshake...that would be

http://www.fhwa.dot.gov

The one you referenced has not much to do with the FHWA! LOL

 

[LPPE]

You know your loads and your spacings. Use your Influence Diagrams.

 

[visitor]

Analysis of multiple moving loads and the position of max moment..etc was not the question in the original post.
The thread was initiated as one of the steps in trying to find out if there is a lane load for this truck.

No answer is better than a non-answer

 

[Qshake]

Yo visitor, if you could read at all you will note that in the beginning of the third paragraph (remember what that is!?) The poster is clearly asking how to a Type 3 Truck load. Later in the same paragraph another question arises regarding the application of a lane load associated with the Type 3 Truck.

As for your comment of "no answer...". Answering the reading understanding and answering question is the essence of this forum, not criticizing others for what amounts to your own laziness!

 

[Qshake]

Oh wait...Vistor, you are the original poster. I guess then I must amend my last comment. You need to better communicate what exactly you wish to know. In reading your post "How do you apply this load" and "Do you put one truck in the middle..." reads an awful lot like you're asking how to apply the truck load. Which incidently is NOT placed in the middle of the span to effect the maximum moment!

Later in the post in that paragraph you introduce the lane load for the Type 3 truck.

I did get the website incorrect. I suggest that you check out

http://www.enron.com

for a new career.

 

[visitor]

you still havent answerd the man!

 

[Qshake]

No, your right, a direct answer has not been given. However, several suggestions were made and the correct address given to the FHWA website where there are phone numbers listed in case the subject matter (lane load) is not given directly.

If you've phoned and looked up the FHWA document that explains the Type S (or 3) Truck at the FHWA publication website and still haven't found an answer...maybe your client knows.