March 31 webinar: Higher-Mode Force Demands in Systems Employing Elastic Strongback Spines

[announce at designsafe-ci.org]

*Webinar: Higher-Mode Force Demands in Systems Employing Elastic Strongback
Spines*



NHERI Lehigh Seminar Series

March 31, 2021 | 12:00 pm – 1:00 pm EST



Speaker: Barbara Simpson <https://cce.oregonstate.edu/simpson>, Assistant
Professor, Oregon State University



Register online at DesignSafe
<https://www.designsafe-ci.org/learning-center/training/workshops/lehigh-ef/2021/higher-mode-force-demands/>
.



About the webinar:



Research has identified the potential advantages of pivoting seismic
force-resisting systems that employ an elastic spine, or “strongback”. The
strongback is represented by a truss or stiff column that is designed to
remain essentially elastic, thus providing an elastic load path to
re-distribute seismic demands across the building height. As such,
strongback systems are expected to result in more uniform drift
distributions, reduced peak inelastic demands, and improved design
flexibility compared to conventional seismic force-resisting systems.



However, since the strongback is designed to remain elastic in every mode,
systems employing strongback spines can be highly influenced by higher-
mode force and acceleration demands that are not well-constrained by
inelastic response. These higher-mode demands can affect
acceleration-sensitive nonstructural components. A series of investigations
were aimed at understanding the nonlinear dynamic response of strongback
systems, including higher-mode mitigation strategies.



At the E-Defense shake-table in Japan, an international team of U.S. and
Japanese researchers tested a moment- resisting frame (MRF) retrofitted
with an elastic spine. The specimen included acceleration-sensitive
hospital equipment. The MRF-spine system was then subsequently modified
with force-limiting connections to alleviate higher- mode accelerations
through controlled yielding. Results demonstrate the influence of
higher-mode effects on strongback and similar systems.



Find more details and register on the DesignSafe website
<https://www.designsafe-ci.org/learning-center/training/workshops/lehigh-ef/2021/higher-mode-force-demands/>
.



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