Patent ID: 8209931

Claim:
In a grid for a suspended panel ceiling adapted for use in seismic prone areas, having main beams, each having a web with a bulb at the top and flanges at the bottom, extending between opposing walls, with the main beams secured to a wall molding on a fixed wall at one side of the grid, and resting on a ledge of a wall molding secured to a slip wall at the opposite side of the grid; the improvement comprising: 1. a superstructure of elements, each of which is formed on and above a main beam in the ceiling grid, and each such element having an upper web extending from each main beam and an upper bulb at the top of the upper web; and 2. a lateral support bar mounted on the slip wall a. extending across the ends of the elements of the superstructure, and b. having laterally spaced keyholes, each of which receives the upper web, the upper bulb, or both an element of the superstructure, wherein such lateral support bar is capable of slidably supporting such superstructure, and the ceiling below such superstructure, at the slip wall, as the ceiling shakes off the ledge of the wall molding secured to the slip wall during a seismic event.