How do I assign one-way slab behavior?
ANSWER: Stress is distributed according to the relative rigidity of supports. For example, when parallel walls connect to either side of a continuous slab, one-way action results. To enforce one-way action, assign small m11 or m22 stiffness modifiers to the slab. These modifiers, available through Assign Area > Stiffness Modifiers, should be applied relative to the local axes and the desired direction of one-way action.