Thesis
Occupant induced lateral amplifications on exterior decks connection stiffness and damping effects
Washington State University
Master of Science (MS), Washington State University
2016
Handle:
https://hdl.handle.net/2376/100466
Abstract
Like many structures, the failure of an exterior deck could result in serious injury or even death. Therefore, it is imperative that these and other like structures are designed for all applicable loads. Physical testing and finite element (FEA) modeling have shown that lateral loads caused by occupants can exceed the capacity of decks designed for wind and seismic events. Parameter sensitivity analyses performed on the models presented in this thesis show that the deck board-to-joist connection properties govern the response of the FEA model, warranting further investigation. Monotonic physical testing carried out on deck board-to-joist connections determined the softened cyclic stiffness and associated equivalent viscous damping (EVD) ratios for 3 connection types. Hem-Fir joists and deck boards were tested with two fastening systems: 10d threaded nails and #10x3" deck screws. Additionally, Hem-Fir joists with Trex composite deck boards and #10 x 2 3/4" Trex composite deck screws were tested. Physical test results showed that for screwed connections, a rotational stiffness of 22000 lb.-in./rad with an associated EVD of 7.3% critical damping is a good estimate of connection parameters. Use of these values with FEA models provided lateral load amplifications that matched well with physical data from previous full-scale deck testing. Rotational stiffness values for the use of nailed deck board-to-joist connections were comparable to that of for screws, but higher EVD values resulted in lower overall simulated amplifications. Stiffness and damping values for the composite board set-up were both higher than that of screws resulting in lower initial amplifications, but the increased mass of the Trex boards led to larger lateral load amplifications with higher substructure stiffness values. A simplified 2D FEA model that produced similar results to the 3D full-scale FEA model was created to readily estimate lateral load amplifications for different deck layouts. An excel spreadsheet developed as a design aid calculates an estimated lateral load amplification for deck sizes and substructure stiffness values that are not within the scope of the full-scale 3D model. Finally, load amplifications for various deck sizes were compiled in an easy-to-use table for use in the lateral design of new or existing deck structures.
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Details
- Title
- Occupant induced lateral amplifications on exterior decks connection stiffness and damping effects
- Creators
- Jonathon J. Waldrip
- Contributors
- Donald A. Bender (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
- 99900525107201842
- Language
- English
- Resource Type
- Thesis