Runner system for fire-resistant suspended ceilings

Claim 1

A CEILING SUSPENSION GRID COMPRISING A PLURALITY OF RUNNERS DISPOSED IN GENERALLY PARALLEL RELATION, A PLURALITY OF COOPERABLE CROSS RUNNERS EXTENDING TRANSVERSELY TO SAID FIRST MENTIONED RUNNERS AND CONNECTED THERETO, A PLURALITY OF CEILING TILE EXTENDING BETWEEN AND SUPPORTED BY SAID RUNNERS, PORTIONS OF SAID RUNNERS BEING EXPOSED BELOW THE CEILING TILES AND THE OTHER PORTIONS OF THE RUNNERS EXTENDING ABOVE SAID CEILING TILES, SUSPENSION ELEMENTS CONNECTED TO THE LAST MENTIONED PORTIONS OF SAID RUNNERS AT SPACED POINTS THEREALONG FOR SUPPORTING THE LATTER THEREFROM, PORTIONS OF SAID RUNNERS ADJACENT SAID POINTS OF SUSPENSION HAVING REDUCED DISTORTION RESISTANCE TO PARTIALLY LOCALIZE DEFORMATION OF THE ADJACENT PORTION OF THE ASSOCIATED RUNNERS POSITIONED ABOVE SAID TILES, PORTIONS OF SAID RUNNERS INTERMEDIATE SAID POINTS HAVING REDUCED DISTORTION RESISTANCE TO PARTIALLY LOCALIZE DEFORMATION OF EXPOSED PORTIONS OF THE RUNNER, AND REINFORCING ELEMENTS EXTENDING BETWEEN ADJACENT PAIRS OF RUNNERS AND MOUNTED UPON PORTIONS OF SAID ADJACENT PAIRS OF RUNNERS EXTENDING ABOVE SAID CEILING TILES TO RESTRICT TWISTING OF THE ASSOCIATED RUNNERS, WHEREBY THE APPLICATION OF HEAT TO THE EXPOSED PORTIONS OF THE RUNNERS, THE RUNNERS WILL TEND TO DIVERGE DOWNWARDLY FROM THE POINTS OF SUSPENSION AND UPWARDLY FROM SAID INTERMEDIATE POINTS TO PREVENT A RUPTURE OF THE CEILING RESULTING FROM RUNNER DISTORTION.