Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

LRFD Live L application on simple span bridge

[Subject Prev][Subject Next][Thread Prev][Thread Next]

I would be glad if anyone can explain or show me a way that I can find
information about application of AASHTO LRFD Live Load on steel bridges,
especially on simple span girders. I'm familiar with Japanese standars, in
which there is only one truck to be considered with the uniform live load.
As far as I know, according to LRFD, 2 trucks must be considered with the
uniform load and the min. distance between the rear axle of one and the
front axle of the other is 15m., and I should consider 90% of the effect of
two design trucks as well as 90% of design lane loading.

Do I need to consider two trucks for positive moment region like it is in a
simple span bridge? Is it for only negatif moment regions? I'm trying to
calculate the live load effect on a 25m(approx. 80 ft) simple span bridge
with 3 lanes and I was asked to compare the live load effects with AASHTO
LRFD. I guess it would be enough to apply only one truck for max. positive
moment but I couldn't be sure. Also for lane loading, I will apply a
9.3KN/m per girder, however, if I try to apply the lane loading on a 3D
model, shall I use a 3m width on transverse direction? (9.3/3=3.1KN/m2?).
In Japan, there is "L" type of loading, in which P1 is taken as 9.8KN/m2
for bending moment (uniformly distributed in 5.5m in transverse, 10m in
longitudinal dir.) and half of that for rest of the width(4.9KN/m2 for 10m
longitudinal), and for rest of the span, similar loading system is applied
but 3.43KN/m2 is considered for P1(named P2). I would appreciate if anyone
can help me to understand or find an LRFD LL loading sample especially for
a simple span bridge.

Best Regards,


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: 
******* ****** ****** ****** ******* ****** ****** ********