Impact factor
Impact factor
(OP)
Do we have any different impact factor for OFF-highway truck bridges, Like state routes etc
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RE: Impact factor
RE: Impact factor
The LRFD spec calls impact something different and I am not sure it is related to speed or weight (I have done limited LRFD design) .
Different states may have requirements that take this into account but you would need to refer to their specific design standard.
RE: Impact factor
The AASHTO Standard Specs based impact on span length with a maximum value of 30%. In reality, impact is due to the motion of the truck and is based on a number of factors such as speed, structure stiffness, friction between wheels and wearing surface.
I've heard it argued that if a truck travels at 5 to 10 mph there is little or no impact effect.
RE: Impact factor
LRFD spec calls it a dynamic load allowance. Deck joints have a DLA of 75%, fatigue and fracture limit states have a DLA of 15% and all other limit states have a DLA of 33%.
RE: Impact factor
If you are using AASHTO, then the answer is no. Check your state bridge design manual. They may have a modification to AASHTO, but I doubt it.
You may be able to use a lighter truck than that required for interstate routes, which would indirectly reduce you impact loading. The impact factor would of couse stay the same.
RE: Impact factor
RE: Impact factor