Patent ID: 7578103

Claim:
A structural system that is energy-absorbent and fire-resistant comprising: a) a main structure having a peripheral wall b) an outer shield comprising: i) a movable portion spaced apart t˜om and surrounding said peripheral wall of said main structure defining a gap therebetween, said movable portion having sliding means to slide against a sliding-plane, ii) a fixed portion surrounding said peripheral wall of said main structure and supporting said movable portion and extending across a substantial portion of the width of said gap, said fixed portion having a fixed plate defining said sliding-plane, c) a crushable layer that is energy-absorbent and fire-resistant filling said gap, and d) an anchorage system that constrains said movable portion of said outer shield from moving and from rotating; wherein said movable portion of said outer shield is provided with a plurality of keys, each of said keys is a projected element protruding across said sliding-plane and nesting in a keyway, said keyway is a cavity selectively dimensioned and located in said fixed portion of said outer shield, said keys and said keyways are hard-wearing elements which resist twisting moments.