AASHTO Design Vehicles

Question

AASHTO Design Vehicles

koodi (Civil/Environmental)

(OP)

29 Sep 03 00:55

1st and mainly:
What is the HL-93 design vehicle?

2nd, with regards to "real vehicles":
What are the changes/differences compared with HS, alternative, and permit loads?

bridgebuster (Civil) · Answer 1 · 2003-09-29 06:47:08

HL-93 is the design vehicle in the AASHTO LRFD Specification. It's the HS-20 truck or tamdem vehicle, combined with lane load. Look at Section 3.6.1.2

koodi (Civil/Environmental) · Answer 2 · 2003-09-29 16:10:33

I do not use AASHTO LRFD. However, yesterday, I was running a piece of software that analyzed the bridge for HL-93 loading--this was the first I'd heard of it.

All I've heard of LRFD, is that it uses strength reduction factors--this must mean it has some new guidelines for steel design. I thought there was going to be some real change when I saw a different design vehicle. But after researching on the net, it became evident it's a HS20 truck.
anyways...

curvbridger (Civil/Environmental) · Answer 3 · 2003-09-29 20:12:30

It is NOT an HS-20. It is the sum of an HS-20 (or an alternate tandem) with a lane load placed in regions of contributing effect.

Curvbridger

koodi (Civil/Environmental) · Answer 4 · 2003-09-29 22:07:34

Beating a dead horse,
Yeah it's and HS20-44.
Giving it another name just confuses the issue.

toddlang (Civil/Environmental) · Answer 5 · 2003-10-13 09:38:17

No, HL-93 is not the same as HS-20. In the AASHTO Standard Spec, the HS-20 truck OR the lane load is used as the design live load. In the AASHTO LRFD, both the truck AND the lane load must be applied at the same time.
To use the HL-93 load with the Standard Spec load factors would be overly conservative and more importantly to use just the HS-20 truck with the LRFD load factors would be unconservative.

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