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http://hdl.handle.net/11375/25991
Title: | Towards More Optimized and Resilient Seismic Design of Buildings With Steel Moment Resisting Frames |
Authors: | Steneker, Paul |
Advisor: | Wiebe, Lydell |
Department: | Civil Engineering |
Publication Date: | 2020 |
Abstract: | While modern building codes have achieved success in preserving life, current code provisions do not explicitly address damage caused by earthquakes, leading to the prevalence of large economic losses. Examples of this limited scope are the changes made to design provisions for steel moment resisting frames (MRFs) following the 1994 pre-Northridge earthquake, where the pre-qualified connection detailing now prescribed for steel moment resisting frames increases the resistance to collapse but still relies on plastic deformations to dissipate energy, potentially limiting the overall improvement in seismic resiliency when compared to pre-Northridge connections. Since the introduction of these pre-qualified connections, several alternative seismic force resisting systems have been proposed which can reduce the expected economic losses by utilizing innovative energy dissipation methods and self-centering behaviour. However, as the use of these low-damage systems is not prescribed in current codes, their application is limited. This thesis begins by examining the improvements in global performance obtained by implementing two examples of low-damage and high-performance MRF connections: the sliding hinge joint (SHJ) and self-centering sliding hinge joint (SCSHJ). Since the goal of these connections is to increase the seismic resiliency of MRFs, their impact is evaluated using several metrics including exposure to longer duration or aftershock earthquakes, as well as measuring their impact on different engineering demand parameters (EDPs). Once this impact has been established, an efficient design implementation is explored where these connections are placed only at locations with large ductility demands, allowing detailing resources to be concentrated at locations where they will provide the largest benefit. After exploring the global performance measured using engineering demand parameters, the economic and downtime reduction benefits obtained from these low-damage and high-performance connections are compared with alternative upgrade strategies. To help identify the most efficient upgrade strategy, a genetic algorithm is applied to define a methodology for optimizing seismic upgrades, including both structural and non-structural options. The optimization methodology considers the benefits in reductions of economic or downtime losses caused by earthquakes, measured using the performance based earthquake engineering (PBEE) methodology, versus the capital costs required to implement each upgrade. Finally, to aid engineers in selecting upgrades throughout all stages of the design process, this optimization methodology is included as the most advanced stage of a proposed seismic upgrade design framework. In the earlier design stages, the framework relies on a new median shift probability (MSP) method to rapidly summarize the effects of structural upgrades on nonstructural components. While the framework and optimization methodology are demonstrated in this thesis by their application to buildings with steel MRFs, they are easily adaptable to consider multiple objectives, building types, non-structural component populations, and building owners. Overall, this thesis provides insight on both the global performance benefits that can be achieved with the newly developed SHJ and SCSHJ connections, and presents a framework to select and optimize various competing seismic upgrade strategies. |
URI: | http://hdl.handle.net/11375/25991 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Steneker_Paul_R_2020_PhD.pdf | 58.98 MB | Adobe PDF | View/Open | |
MSP_Steneker_Paul_R.xlsx | 58.71 MB | Microsoft Excel XML | View/Open |
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