LRFD Braking Force

[connor61]

Good morning -

When designing a pier for a two span continuous structure, the controlling load for the vertical reaction is a lane load with TWO design trucks (one in each span).

When computing the BRAKING FORCE, do you use the axles for a SINGLE truck or the TWO trucks?

It is my understanding that the BR is computed using only the SINGLE truck.

Thank you.

 

[crossframe]

A single truck... in each lane.

Look at the load combinations and evaluate each of them for 1 lane, 2 lanes, etc.

 

[civilperson]

During hurricane evacuation in Louisiana, all lanes of the interstate bridge are outbound and the maximum force from braking uses all possible lane widths in the same direction, (including shoulders and partial lanes from 11 foot wide design lanes).

 

[shaurya241100]

braking forrce is a function of load on the bridge and also to calculate the forces resisted by the pier/abut, it will depend on the articulation system. The braking force will go to the support where bearings are fixed. If it is an integral structure it will be resisted by the support in accordance with their stiffness.