Distributed Knee-Braced (DKB) system as a complete or supplemental retrofit of soft-story wood-frame buildings

M. Gershfeld, C. Chadwell, J. Van De Lindt, W. Pang, E. Ziaei, M. Amini, S. Gordon

Research output: Contribution to conferencePaperpeer-review

Abstract

The NEES-Soft, NSF sponsored project, evaluated the performance of various retrofit schemes for "soft-story" light wood-frame buildings subjected to seismic loading as one of its objectives. The DKB (Distributed Knee-Braced) system retrofit was one of the retrofits evaluated. This system consists of an assembly of light wood-frame knee-braced frames placed so as to reinforce an existing deficient line of resistance. The individual knee-braced frames are constructed by reinforcing existing wall studs of the existing soft-story building with additional stud(s) and connecting them to the existing floor joists with a new diagonal 2x wood members. The reinforcement of the members and connections along the knee-braced frame load path are designed to exceed the capacity of the knee-brace connection to the stud assembly and floor joist, thus creating a ductile load path fuse at these connections. The DKB system was numerically evaluated using 2D non-linear dynamic analyses. The numerical results were validated using, reversed-cyclic tests of two full scale DKB configurations and a follow up shake table test of one of the configurations. The four-frame 10ft DKB system was able to develop maximum lateral load capacity of approximately 2,400 lbs (1088 kg) at 4.5% drift and at 7.5% drift was still able to support close to 1,000 lb (454 kg). The findings of this research suggest that the DKB system, for certain structural archetypes, can be an effective alternative to other more traditional "soft-story" timber structure retrofits.

Original languageEnglish (US)
DOIs
StatePublished - 2014
Externally publishedYes
Event10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering, NCEE 2014 - Anchorage, United States
Duration: Jul 21 2014Jul 25 2014

Conference

Conference10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering, NCEE 2014
Country/TerritoryUnited States
CityAnchorage
Period7/21/147/25/14

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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