Improving the Seismic Resilience of Steel Braced Frames Using Innovative Technologies

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The post-earthquake structural resilience started to be of particular interest to governments and private businesses owners after the 2010 Chile earthquake (M 8.8), the 2011 Tohoku earthquake in Japan (M9), and the 2011 Christchurch aftershock earthquake in New Zealand (M6.3). Researchers concluded that a resilient structural system should be able to: reduce probabilities of structure failure, reduce consequences from failures, and reduce recovery time. To achieve this goal, new developments in the field of damage-resistant technologies are required. Furthermore, the next generation of damage-resistant buildings should be able to self-center and to be reparable at an affordable cost. Despite of energy dissipation capacity, commonly, all concentrically braced frame (CBF) building structures including those with installed passive energy dissipation devices have shown high residual interstorey drift when subjected to large magnitude earthquakes. Thus, the main objective of this proposal is to develop self-centering devices for CBF buildings, to characterize the new building system, as well as to quantify their seismic performance factors. More specifically, in this application, two innovative self-centering systems comprising friction ring springs cartridges and dual-core compressed elastomer devices are proposed. Both devices are able to act in dual direction, to self-center the system and to provide flag shape hysteresis response. These proposed self-centering systems will be employed to self-center the CBFs with installed dissipative pin connections and CBFs equipped with friction damper devices. In addition, an innovative cost-efficient self-centering energy dissipating brace member is envisioned and designed to replace braces of traditional CBF building systems. Design guidelines, quantification of buildings seismic performance factors, as well as, a framework for life-cycle based design will be provided. For the life-cycle based design method it is intended to consider safety-related performance goals in terms of the risk of life loss and financial losses including repair and downtime rather than collapse. The resulted performance curves will be a valuable tool for decision-makers.