Method of solution

Moment and shear forces on permanent and variable load is saved during the calculating, and the different load cases are then put together according to the certain load combinations. The standard load-combinations are as follows:

Every other span:

Every other span with permanent load and every other span with permanent + variable load (2 load combinations).

Neighboring spans:

Alternated two neighboring spans with permanent + variable load and others with permanent load (n - 1 load combinations where n = number of spans).
The program calculates stiffness matrix and equivalent joint loads for the beam elements. The equations are solved by a matrix inversion, and the joint forces of the different load combinations can be calculated.

After the solution of the end moments for each load combination moments and shear forces within each span will be calculated from the end moments and current loading.

Using the values from the different load combinations maximum section forces and support reactions are calculated. Maximum column reactions (if any) are calculated at the same time.

The calculation result is visualized as maximum diagrams for moment and shear force.