Case Study #2 – Traffic Load Optimisation

In the finite element model below, it is possible quickly to define a set of load combinations that will give the live load bending moment envelope for one of the box beams.

Using Sam's innovative optimisation process together with the composite results facility
see Case Study #4) the optimisation can be done in less than two minutes.

The steps of the process are simple and intuitive giving maximum control with minimum input.
The process can be summarised as follows:

1. Define a composite member of the FE box (shown in red, with its axis in blue).
2. Create bending influence surfaces for each point along the composite member axis.
3. Set/change the optimisation parameters if necessary (generally set once for each project).
4. Create the required load patterns and envelopes including all necessary load and lane factors.
   A single mouse click invokes the process to achieve this.

There are many features included in the optimisation module, some of which are:

• All possible traffic load combinations are considered.
• Any special vehicles can be defined and included in the optimisation process.
• The lateral position of assessment lane loads can vary along the span. This ensures maximum effect.
• The ability to define vehicle load convoys ensures the correct axle orientation for curved carriageways.

Of course the main benefit of using the process is the time saving achieved over using more traditional or non-integrated optimisation programs.