Moving and live loads

[pnacht]

When designing a bridge, the "live" loads are separated into two parts (usually). A heavy truck (with definitions according to different codes) and a distributed liveload which represents ordinary everyday cars and lighter vehicles.

From what I understand, in Robot one does this analysis of the truck with Loads > Special Loads > Moving Loads, which gets the truck and moves it along a line, therefore creating what I'm now going to call the Truck Envelope.

How does one go about creating the remainder of the live load? Do you have to create different cases for loading in the different regions of the bridge (case 1 - Between Beams 1-2 ; case 2 - Between Beams 2-3, case 3 - Between Beams 3-4, etc... including separating between pilars)? Or is there a way of giving Robot a load value (in a similar manner to the Truck) and it creates an envelope with it by applying it where necessary?

[Rafacascudo · Accepted solution]

It won´t do automatically.

   If it is a straight bridge , with bar elements only , you can create a live loading for each span and use automatic combinations(using the rules) to cover all possible combinations of loading.

   For a special(curved )bridge , you can always use the influence lines generated according to the forces/reaction/displacement you want , and load it only on bar segments for the desired effect.

If it is a 3d bridge with slabs ,The most precise way  is using Loads/special Loads/Load pattern . Then you can have any influence surface you want and set a contour load to get the max/min effects