Objective - To implement all 16 recommendations from the NIST Joplin tornado investigation, at the earliest possible date based on code and standard development cycles, by: (1) conducting research and development to provide the technical foundation for improved guidelines, standards, codes and (2) developing, or coordinating the development of, guidelines, national standards, and code change proposals; and (3) coordinating/championing their adoption in the national model codes.
What is the new technical idea? While progress has been made on several of the recommendations during the first phase of the Joplin Implementation Project (completed in FY19), development of the new probabilistic tornado hazard maps has been the primary focus. Now that the R&D to develop the map methodology is finished and the draft maps have been delivered to key stakeholders, the second phase of the project (beginning in FY20) will expand the focus to include several additional recommendations, as follows:
- Tornado Hazard Maps (R3): With completion of R&D to develop the map methodology and draft maps in FY19, the remaining tasks in the second phase to complete the maps recommendation are in the technology transfer domain, including dissemination of the tornado maps and having the maps and associated tornado load provisions (see R6) incorporated into building codes and standards.
- Enhanced Fujita Tornado Intensity Scale (R4): Standardize the Enhanced Fujita scale and improve the scale through the addition of wind speed estimates for new and existing Damage Indictors based on scientific and quantifiable methods.
- Performance-Based Tornado-Resistant Design Standard (R5) and Methodologies (R6): In phase 2 of the project, utilizing a holistic design approach requiring all building components and systems to meet or exceed the same performance objectives specified for that building, NIST will continue working closely with the American Society of Civil Engineers (ASCE) on creating performance-based design (PBD) criteria for extreme winds (R5), and lead development of a tornado wind load design methodology (R6) consistent with the technical basis of the new tornado hazard maps.
- Tornado Shelter Standard for Existing Buildings (R7): Expand the current storm shelter standard to encompass installation of shelters within existing buildings.
- Guidelines for Selection of Best Available Tornado Refuge Areas (R9): Expand on the tornado damage modeling conducted as part of the map development to create a fragility-based methodology and tool for selection of best available tornado refuge areas within existing buildings.
- Guidelines for Public Tornado Sheltering Strategies (R8): Develop guidelines that enable communities to create safe and effective public sheltering strategies.
- For the remaining recommendations, with other agencies designated as lead, NIST will actively participate as either coordinator/convener/facilitator/committee member to make sure necessary work/code change proposals get completed in a timely manner consistent with the standard and code development cycles.
What is the research plan? The research plan to implement the several recommendations identified above is as follows:
- Tornado Hazard Maps (R3). The remaining tasks focus on technology transfer and will be conducted in parallel. These tasks include: a) working through the standards and codes processes to get the tornado maps and associated load provisions into ASCE 7-22 and the 2024 International Building Code; b) writing technical publications detailing the map development methodology; and c) dissemination of this information to a broader audience of stakeholders through articles in technical magazines and newsletters, conference presentations, and other approaches.
- Enhanced Fujita Tornado Intensity Scale (R4): Improve the EF Scale methodology by establishing a more scientific and quantifiable approach to the development of Degree of Damage (DoD) wind speed estimates for existing and new Damage Indicators (DIs), through development of a new standard intended for adoption by the National Weather Service. Adapt the damage modeling research and fragilities for key DIs from development of the tornado hazard maps into ‘Smart DIs’, where better wind speed estimates can be obtained by inputting more information about the building or structure, its connections, and other architectural and structural features.
- Performance-Based Tornado-Resistant Design Standard (R5) and Methodologies (R6): Continue collaboration with the PBD Task Committee of ASCE 7 Wind Load Subcommittee, to expand the guidance being developed for more general wind PBD to specifically include tornadoes (R5). For R6, a) develop a tornado wind load design methodology, consistent with the assumptions underpinning the new tornado hazard maps, and propose it for incorporation into ASCE 7-22; and b) work collaboratively with FEMA to develop and publish a NIST/FEMA tornado design guide, consistent with performance objectives developed under R5.
- Tornado Shelter Standard for Existing Buildings (R7): Propose changes to the 2020 edition of the ICC 500 Standard for Design and Construction of Storm Shelters, to increase the scope and insert provisions governing the installation of tornado shelters within existing buildings.
- Guidelines for Selection of Best Available Tornado Refuge Areas (R9): Build on the existing proof-of-concept for a fragility-based best available refuge area selection methodology, incorporating and expanding the tornado damage modeling conducted as part of the map development process. Validate the methodology against observed life safety performance of buildings, including existing data from the Joplin and Moore tornadoes. Collaborate with FEMA to incorporate this engineering-based methodology and associated guidance into a new edition of FEMA P-431, Tornado Protection: Selecting Refuge Area in Buildings
- Guidelines for Public Tornado Sheltering Strategies (R8): Conduct a series of workshops to identify opportunities, challenges, and best practices associated with design and operation of public tornado shelters. In collaboration with FEMA, publish guidelines that will enable communities to create safe and effective public sheltering strategies. The guidelines will address planning for siting, designing, installing, and operating public tornado shelters.