Thesis
Seismic retrofitting downslope hillside dwellings with uphill anchorage and cripple wall wood structural panel sheathing
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/103764
Abstract
Hillside dwellings are prone to severe levels of seismic damage due to structural behavior issues that arise from bearing on a stepped or sloped foundation. Compared to homes built on a flat site, they are significantly more likely to collapse or to be red-tagged by building inspectors following a major seismic event, deeming them inhabitable. This research looks to increase the chance that these homes are available for shelter following a major seismic event by expanding on a retrofit technique that was developed by the City of Los Angeles Hillside Task Group in response to the 1994 Northridge earthquake. The retrofit approach anchors the base-level diaphragm to the uphill foundation with robust anchorage elements at the ends of the uphill foundation, named primary anchors. Redundant anchorage elements are also spaced along the uphill foundation, named secondary anchors. This research further evaluates the behavior of this retrofit for suggestions and proposes wood structural panel sheathing is additionally applied to the interior face of the downhill cripple walls. Three-dimensional finite element models of hillside dwellings were created in the program Timber3D by utilizing past testing results on the load-displacement behavior of various components that describe the dwelling's load path. The performance of models was evaluated for the existing condition as well as various retrofit conditions. Performance was quantified by primary criterion and secondary criteria for comparative use. The primary criterion monitored the models for probability of collapse at a seismic event with Maximum Considered Earthquake (MCE) intensity. The secondary criterion monitored how likely the structure was to be yellow-tagged or red-tagged at various intensities of ground motions. The proposed retrofit technique reduces probability of collapse at MCE by up to 70% and decreases the likelihood that cripple walls are yellow or red-tagged following a moderate event. This research assumed that sites were geotechnically sufficient and concrete strength was not implicitly modeled. However, performance of the retrofit with deep and shallow foundations was simulated and found adequate. It is suggested that this retrofit technique is only applied to one-story light-frame dwellings to prevent anchorage demand forces being too high for the uphill foundation.
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Details
- Title
- Seismic retrofitting downslope hillside dwellings with uphill anchorage and cripple wall wood structural panel sheathing
- Creators
- Taylor Charles Vincent
- Contributors
- J. Daniel Dolan (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525194301842
- Language
- English
- Resource Type
- Thesis