Protecting the ladder slab is one aspect, mainly to weaken the influence of the ladder slab as a diagonal brace on the structure, so that the mechanical properties of the structure under earthquake meet our design intention. After all, it is very troublesome to simulate the whole cast-in-place stairs in the anti-specification to participate in the actual overall structure calculation. If the sliding bearing of stairs is well realized, the diagonal bracing function of stairs will not exist or be weakened, and the influence of stairs on structural stiffness will not be considered in structural calculation.