Load systems

A mobile load system is composed of one or more load groups. For each group, a distributed load and several concentrated load impulses can be defined. The distance between individual load impulses is fixed and is defined relatively from a reference point. The distance between individual groups can be fixed or can vary to simulate the real situation on a railway or highway bridge. The final purpose is to position the load systems into such a position so that the produced effect on the structure is extreme.

The program first determines the influence lines for each effect, result or reaction for each section of a structure element. Those influence lines, defined by an ordinate for a load position in regard with a fixed section, are evaluated for all internal forces, reactions and deformations. For each influence line, the process determines preponderant parameters like the position of the sign switching, that defines the positive, and the negative part of the influence. For each field, the area under its curve is determined. The load system is now placed (for a given section and a given effect) on the influence lines and is positioned until the extreme is found.