ECCENTRIC SEISMIC POUNDING OF SYMMETRICAL BUILDINGS

Results of a parameter study on eccentric pounding of two symmetric si ngle storey systems under seismic excitation are presented. Linear beh aviour is assumed, and pounding effect is considered using the restitu tion coefficient approach. The effect of impact eccentricity is studie d on two sets of symmetric models symmetrically and asymmetrically ali gned with respect to each other for several gap widths, period depende nt gaps and three values of the torsional-to-lateral frequency ratio. Two time histories are used for input. On the whole it was found that impact eccentricity amplifies the response relative to symmetric impac t but the effect is not proportional to first impact eccentricity. Als o, increasing gap width is likely to be effective when the separation is sufficiently wide practically to eliminate contact. Larger torsiona l rigidity tends to lower response amplification. SRSS code-type gaps appear to be adequate, or even excessive, when the design spectrum is compatible with the expected earthquake record at the site.