Lane Load on Box Culverts?

[pjlefeb]

Hello,

I am running a structural design on a box culvert, and I have a question on live load application using the old AASHTO Standard Specifications 17th ed. (Yes, I realize that most places are using the LRFD specs now. But anyway...)

The specs say that truck -or- tandem -or- lane should be applied to determine the maximum force effects. But I have found in a couple different places that the lane load need not be included for the design of box culverts and other buried structures - it is meant for the design of deck slabs. Here's one place:

http://precast.org/2010/07/hl93-truck-loads-vs-hs20-truck-loads/

The lane load is also ignored in ASTM C1433, and in FHWA's popular "Boxcar" design program. I cannot find any place in the code where AASHTO specifically says that the lane load can be ignored. Does anyone know where??

Thanks!

 

[cap4000]

The HS lane loading condition controls the design for the longer span bridges. The cutoff is over 140 foot span +/- for bending moments and over 127 feet for shears. What is the length of your culvert? Typically it would be truck axle loads that would control for small culverts.

 

[pjlefeb]

No, the culvert is small.

Are you saying that the decision of ASTM C1433 to check only the tandem and truck is because by inspection the lane load will not control?

 

[pjlefeb]

In case anyone was wondering, I finally found it. In section 16.4.4.2.3,

"Live loads shall be either the AASHTO HS-Series or the AASHTO Interstate Design truck loads."

No mention of lane load.