RESPUESTA ACOPLADA DE TRASLACIÓN Y TORSIÓN DE ESTRUCTURAS ASIMÉTRICAS INCLUYENDO LA INTERACCIÓN CON EL SUELO

SUMMARY By considering the effects of soil-structure interaction, the coupled lateral and torsional response of asymmetric structures placed on a soil layer under seismic excitation is studied. The system investigated consists in a torsionally coupled single oscillator with embedded foundation in a soft stratum over an elastic half-space, subjected to SH waves with different angles of incidence. Both the inertial and kinematic interaction effects are considered. Numerical solutions are calculated for a large number of system configurations, taking as control motion the great 1985 Michoacan earthquake recorded at three sites representative of the transition and soft zones in the Valley of Mexico. The dynamic amplifications of static eccentricity and the base shear ratio between the coupled and uncoupled shears are evaluated and compared with the current code provisions for building structures (Normas Tecnicas Complementarias para Diseno por Sismo del RCDF, Gaceta Oficial Del Distrito Federal, 1995). It is shown that, at least for linear behavior of the structure, the design provisions for torsion may underestimate the maximum structural response when the interaction effects are of extreme significance, as happens in Mexico City.