| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | July 11, 2017 |
| Latest Amendment Date: | July 14, 2020 |
| Award Number: | 1726326 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Joy Pauschke
jpauschk@nsf.gov (703)292-7024 CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | July 15, 2017 |
| End Date: | June 30, 2022 (Estimated) |
| Total Intended Award Amount: | $1,007,491.00 |
| Total Awarded Amount to Date: | $1,144,872.00 |
| Funds Obligated to Date: |
FY 2020 = $137,381.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
4333 BROOKLYN AVE NE SEATTLE WA US 98195-1016 (206)543-4043 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
4333 Brooklyn Ave NE Seattle WA US 98195-2700 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
Engineering for Natural Hazard, ECI-Engineering for Civil Infr |
| Primary Program Source: |
01002021DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
In extreme events, such as major earthquakes or tsunamis, public safety is a primary concern. A major subduction zone earthquake could cause a large tsunami, which could render constructed infrastructure near the coastline, traditionally designed for only seismic loads, to be severely damaged and result in loss of life. In coastal regions at low elevations, it may be difficult to quickly move to higher ground in the short time between the initial ground shaking and the arrival of a tsunami from a subduction earthquake. However, a vertical evacuation structure (VES) could provide refuge, with the most promising VES for large coastal populations being buildings with lower stories capable of resisting the sequential earthquake demands and tsunami loads. This research will investigate a new structural system for a building to serve as a VES, where the structural elements are continuous from the end of the pile to the top of the structure. This new system will use the above-wave-height stories for evacuation; the lower (below wave) stories will use connections that allow walls and slabs of the lower, non-evacuation floors to "breakaway" at the highest water level. Although counterintuitive, this breakaway system will reduce the tsunami load demands on the structure, further protecting the building and its occupants. This research will investigate the interactions of the structure, soil, and tsunami waves for both traditional systems designed only for seismic loads and the new breakaway structural system. The results of this research will provide first-of-its kind data for this new type of VES, which can improve life safety in tsunami-prone regions and provide course-ready material for graduate-level classes and seminars for researchers and practitioners. Data from the project will be archived and made publicly available in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (http://www.designsafe-ci.org).
Although evacuation structures have been built in tsunami-prone regions in Japan and the United States, they are typically low-rise structures with limited shelter capacity. In contrast, taller structures could serve dual purposes, such as a hotel with lower stories housing retail or conference rooms, with upper levels designed for evacuation. Under earthquake loading, buildings are expected sustain damage in the maximum credible event and, unless specific to the site, soil-structure interaction is neglected. This design philosophy would not serve for a VES, which must be designed to: (1) remain damage-free during the maximum credible earthquake, (2) sustain the maximum considered tsunami at the lower floors, including horizontal and vertical forces, where initial research shows that these tsunami force demands can be two to five times the design earthquake forces, and (3) account for changes in the stiffness and strength of the soil due to liquefaction and scour. This research will address the fundamentals of sequential earthquake and tsunami hazard building performance to serve as a VES, accounting for full nonlinear soil-structure-wave interaction. Two structural systems will be studied: exterior concrete walls, which are a traditional structural solution for seismic loads, and a new structural system utilizing continuous concrete filled tube pile-column frames with breakaway connections at the floors below the inundation depth, tuned to fracture at specific loading resulting from hydrostatic buoyancy. The research activities will involve the following: (1) investigate fundamental characteristics of the soil-structure system through computational simulation, (2) experimentally study tsunami demands on the structure using the NHERI Large Wave Flume at Oregon State University, (3) analytically couple the tsunami demand and structure-soil response analyses using the NHERI Computational Modeling and Simulation Center resources, and (4) combine the findings to evaluate current and establish new design methodologies for VESs subjected to sequential earthquake and tsunami hazard loading.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
In extreme events, such as major earthquake or tsunamis, public safety is a primary concern. An article in July 2015 of the periodical The New Yorker entitled “The Big One” proclaimed that a major subduction zone earthquake could cause a major tsunami, which would render infrastructure well beyond the coast “useless”. In coastal regions at low elevation, it can be impossible to quickly get to higher ground in the short time between the initial ground shaking and arrival of a tsunami from a subduction earthquake.
Vertical evacuation structures (VES) can provide refuge to people in these areas. VES take a range of forms with the most promising for large populations being buildings with lower-levels capable of resisting the sequential earthquake demands and lower-intensity tsunami loads. However new structural systems are needed to formidably resist tsunami loads to protect lives. Rather than using conventional building systems, a new structural type is being researched where the structural elements are continuous from the end of the pile to the top of the structure and the above-wave-height stories which are used for evacuation. A unique aspect of the building are connections that allow walls and slabs of the lower, non-evacuation floors to “break away” at the highest water level. Although counterintuitive, this break away system reduces the tsunami demands, further protecting the building and its occupants.
To fully research these systems and provide building-code ready engineering expressions for use by public agencies and design engineers, the research program studied the interactions of the structure, soil and tsunami waves. First a large-scale “wave tank” (funded and supported by the NSF) capable of simulating a range of tsunami waves was used to investigate the physical interaction. These results were used to building computer-based models, where computer algorithms will simulate the nonlinear range of the building and the soil and use new computer techniques to simulate the sequential demands of the earthquake and the tsunami. The results of this research resulted in first-of-its-kind data for VES and is expected, after full implementation, to both improve life safety in tsunami-prone regions and provide course-ready material for graduate level classes.
The primary outcomes of this reserach project were as follows:
1. A new, validated design approach and system for tsunami resistant regions. VESs must be designed to: (1) remain damage-free during the maximum credible earthquake, (2) sustain the maximum considered tsunami at the lower floors, including horizontal and vertical forces, where initial research shows that these tsunami force demands can be 2 to 5 times the design earthquake forces, and (3) account for changes in the stiffness and strength of the soil due to liquefaction and scour.
2. The research team developed a new frame that accounts for the earthquake demands and can sustain scour (loss of soil). Two structural systems were studied: exterior concrete walls, which are a traditional solution, and this novel system utilizing continuous concrete filled tube (CFT) pile-column frames with breakaway connections at the floors below the inundation depth, tuned to fracture at specific loading resulting from hydrostatic buoyancy. The frame was superior to the wall in three ways: (a) reduced tsunami demands, (b) accommodation of soil loss (sour), and (c) reduced hydrostatic demands using tuned, breakaway connections.
3. A new computer method to link the tsunami demands to the nonlinear response of the VES. This method allows the engineer to account for the sequential earthquake and tsunami demands, interaction of the water from the tsunami, the soil supporting the deep foundations and the structure above the soil that serves as a refuge for the community adjacent to the coast.
4. A new slab-column connection for flat plate structures in earthquake and tsunami-prone regions. This connection can sustain large, cyclic drift demands which is critical to preventing collapse of reinforced concrete structures. In addition to being used in areas with large earthquakes, it is being adopted to strengthen flat plate structures in coastal regions to prevent a future collapse such as experience by the Champlain Towers South building in southern Florida.
5. The results from this study are being integrated with complementary research to develop a new course and its curriculum on tsunami-resistant design.
Last Modified: 11/26/2022
Modified by: Dawn Lehman
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