EFFECT OF FLANGED WALLS ON THE SEISMIC PERFORMANCE OF TALL BUILDINGS

Flanged walls are a common feature in concrete and masonry constructio n that require special consideration because of the distinct nature of their response to earthquake forces. Flanged walls typically have dif ferent strength, stiffness and ductility capacities in the two opposit e directions when loading is parallel to the web. Their effect on seis mic response is particularly critical in tall buildings because the he ight of the walls usually ensures that the flanges are fully effective under lateral loads. An existing building is used to investigate the effect of flanged walls on building response, A performance-based appr oach with three levels of ground motion is used, and nonlinear time hi story analyses are utilized to determine the structural and non-struct ural damage for each level of ground shaking. Structural damage is det ermined with limit state methodology while non-structural damage is ev aluated by correlating inter-story drifts and floor accelerations to d amage in the non-structural building components. The analyses show tha t buildings with flanged walls will incur less structural damage from moderate earthquakes than corresponding buildings without flanged wall s. On the other hand, major earthquakes that impose large ductility de mands may cause significantly more structural damage in flanged walls. Nonstructural damage in flanged-wall buildings is about 20-40% greate r than that in buildings without flanged walls. The increase in non-st ructural damage is also greater when there are large ductility demands , (C) 1997 John Wiley & Sons, Ltd.