Balancing Lateral Loads Using Tendon-Based Supplemental Damping System

A new design and retrofit concept that deals with the placement and functional attributes of dampers for the seismic protection of buildings is presented. The configuration for the proposed concept is referred to as load balancing prestressed tendon-fuse + damper system. The system is based on the notion of prestressed load-balancing and uses a combination of tendons, fuse-bars, and dampers; the latter preferably possessing recentering and preload characteristics. It is shown that the system has a direct effect in reducing the overturning moment demand on the main structural elements. The new approach is first contrasted with the concept that is currently used by designers and advocated in FEMA 273. Next, an overall strategy is presented for the various phases of the design process. This includes the facets of conceptual and preliminary design as well as the final design verification process. The efficacy of the preliminary design phase is improved by a well-conceived 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 configuration details. Finally, the seismic design and evaluation of a nine-story steel building is presented as an example of the applicability of the proposed design algorithm and system configuration.