Balancing lateral loads using tendon-based supplemental damping system

A new design and retrofit concept that deals with the placement and functio nal attributes of dampers for the seismic protection of buildings is presen ted. The configuration for the proposed concept is referred to as load bala ncing prestressed tendon-fuse + damper system. The system is based on the n otion of prestressed load-balancing and uses a combination of tendons, fuse -bars, and dampers; the latter preferably possessing recentering and preloa d characteristics. It is shown that the system has a direct effect in reduc ing the overturning moment demand on the main structural elements. The new approach is first contrasted with the concept that is currently used by des igners and advocated in FEMA 273. Next, an overall strategy is presented fo r the various phases of the design process. This includes the facets of con ceptual and preliminary design as well as the final design verification pro cess. The efficacy of the preliminary design phase is improved by a well-co nceived single-degree-of-freedom idealization of the structural system. The general normalized design parameters for the supplemental system are then transformed for the multi-degree-of-freedom system based on specific config uration details. Finally, the seismic design and evaluation of a nine-story steel building is presented as an example of the applicability of the prop osed design algorithm and system configuration.