" Floating " Stiffness Matrix

If you use self-equilibrium loadings, RAM Concept creates an internal floating stiffness matrix in addition to the regular stiffness matrix. The floating stiffness matrix considers the slab, but not the supports above or below the slab. RAM Concept also adds some minimal supports to the matrix to make it stable.

Minimal Supports

The minimal supports that RAM Concept adds to the floating stiffness matrix are located at real support locations, but not at every real support location. Typically, RAM Concept adds three supports to provide full stability, but not to provide any restraint.

The motivation for adding the minimal supports at the same location as real supports is that these locations are likely to be locations where self-equilibrium loads are applied, so any reactions at these locations can typically be considered as "corrections" to the self-equilibrium loads.

Punching Check Reactions

Punching checks consider the loads applied at the punching check location in their reaction calculations. Punching checks are the only "support" that have reactions from self-equilibrium analyses.

Displacements

RAM Concept reports all displacements for self-equilibrium loadings as zero. Self-equilibrium loadings have no effect on the displacements calculated for load combinations or rule sets.

Pattern Loading

Pattern loading can be used in a self-equilibrium analysis, but it should almost never be used. When used, all patterns should contain a self-equilibrium set of loads.