Design and retrofit methodology for building structures witn supplemental energy dissipating systems

The study described in this report on focuses on fundamental issues related to the design and use of supplemental damping devices in building structures. The principle objective is to develop a generic/practical analysis and design methodoly for structures that considers structural velocities and equivalent viscous damping of the devices. These two issues are explored in depth. Tools to transform the spectral velocity to an actual relative structural velocity are provided, and simple design procedure which incorporates power equivalent linear damping based on actual structural velocities is presented. The effectiveness of the design methodology is demonstrated with a retrofit design example using a supplemental load balancing tendom configuration

Experimental investigation and computational modeling of seismic response of a 1:4 scale model steel structure with a load balancing supplemental damping system

An experimental study to investigate the seismic behavior of steel structures under the simulated ground motions is described. It is argued that damper distribution should be based on: (i) either the interstory deformations or story shears, and (ii) the overturning moments generated by the lateral inertia loads. The former method was implemented in a non-ductile reinforced concrete frame (Pekcan et al., 1995), while for the latter method an innovative prestressed load-balancing tendon system was introduced in this report. Approximate alternatives were experimentally explored on a model steel structure. This load-balancing supplemental system consists of prestressed-draped tendons in the shape of the overturning moment diagram. The tendons are connected in series with the nonlinear dampers and sacrificial fuse-bar. It is concluded that the load-balancing tendon-fuse+damper system is an appropriate cost-effective method of mitigating the earthquake induced demands on a steel frame. By careful detailing, it is possible to ensure that under design earthquake loads the structure remains elastic, while under maximum credible motions fracture of the steel frame welded connections can be avoided