You design concrete floors manually by calculating the resultants (moments, shears and axial forces) of a load combination and applying the appropriate code rules and formula. You select code rules based upon the type of member (reinforced slab, post-tensioned beam, etc.) and the type of load combinations. For example, codes intend some load combinations are for strength design and others for serviceability design.

RAM Concept uses a similar method. It sorts code rules into sets of rules and applies them to the resultant envelopes of load combinations. Thus, a rule set design is one or more code rules applied to the resultant envelope of one or more load combinations.

For example, the set of code formula for bending and shear strength is the strength rule set. RAM Concept applies this rule set to the envelope of all "factored" (or ultimate) load combinations. The strength rule set does not apply to service load combinations.

You design most floors or members for more than one rule set. For example, a post-tensioned floor is usually checked for initial service stresses, service stresses and strength, all with different load combinations.