EARTHQUAKE DAMAGE, MEXICO CITY, SEPTEMBER 19, 1985

Failure of Top Floors, Hotel Continental, Mexico City

Top failure of Hotel Continental (constructed in 1950). Top floors of buildings are particularly vulnerable because (1) upper floors are displaced more than ground level floors during earthquakes. (2) The resonance frequencies of the buildings coincide with the ground vibrations leading to large amplification of oscillations. (Such displacements often culminate in a whip-like effect.) (3) Upper floors often have smaller and weaker load-bearing components. (4) The length of this earthquake event gave time for development of torsional vibrations due to asymmetric distribution of masses and elasticity in the high-rise buildings. Photograph credit: C. Arnold, Building Systems Development, Inc.