Earthquake Behavior of Suspended-Floor Buildings

The earthquake integrity of a new type of multistory building, referred to as suspended-floor high rise, is investigated. In these structures floors are supported by steel tension elements called hanger straps which are draped over the end walls of two reinforced concrete core towers. Limited-capacity connecting elements called bumper bars couple the motions of the suspended floors and the supporting core towers. A three-dimensional analytical model and pertinent dynamic analysis techniques are presented. Finite element representations of the core towers are incorporated into substructure models which feature all basic components of the system. The model is assembled using series elimination, and the linear dynamic response to several earthquake loadings is provided to illustrate structure behavior. Dynamic testing performed at the site of two existing suspended-floor buildings produced natural frequencies and damping values. Comparison of measured and computer-generated frequencies demonstrates the validity of the analytical model.