Load Paths Compatible with Full Building Lateral Analysis

The most common use of self-equilibrium analyses is to ensure that a load path in RAM Concept is consistent with a load path in a lateral analysis performed by a separate program.

If a lateral analysis of a building (perhaps using RAM Frame) is performed, and that analysis considers the slab to be part of the lateral load path, the slab - including the slab-column connections - needs to be designed to resist the forces and moments determined in the lateral analysis. This design can be performed using a self-equilibrium analysis. The forces/reactions from all of the supports (above and below the slab) onto the slab are considered as loads to the slab, any forces directly applied to the slab (such as a story-force in a seismic analysis) are also included.

The result of this self-equilibrium analysis is a slab load path that is fully consistent with the lateral analysis of the entire building. The distribution of forces (and the displacements) within the slab may not match those in the building lateral analysis, but the distribution of slab forces in RAM Concept t is almost always more accurate than those predicted in the full-building analysis.

Other Uses

While there are other potential uses of the self-equilibrium analysis, they are rare and not covered in this manual.