Publication: State of the Art and Research Needs in Design for Tornadoes to Improve Community Resilience: Structural Engineering Institute Workshop Report
9:30am–12:00pm – State of the Art Presentations/Panel Discussions
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Case Study: “Tornado Wind Speeds for Engineering Design: Research Topics” – Larry A. Twisdale, Jr., Consultant [25 min = 15 min PPT + 10 min Q&A]
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Case Study: “Tornado Loads in Practice: Commercial Building Design” – John O'Brien, P.E., S.E.; PES Structural Engineers [25 min = 15 min PPT + 10 min Q&A]
15-Minute PICTURE + COFFEE BREAK
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Case Study: “Building for Tornadoes: Engineering Resilient Communities through Codes” – Anne Cope, Ph.D.; IBHS Chief Engineer [25 min = 15 min PPT + 10 min Q&A]
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Panel Discussion: “The Next Generation of Tornado Provisions: What's Possible?” [45 min = 30 + 15 min Q&A]
LOCATION: ASCE Bechtel Conference Center, 1801 Alexander Bell Drive, Reston, VA 20191
SEI Tornado Design Workshop – Breakout Session Descriptions, Reading List, and Participants
Session Descriptions:
Breakout Session Topic 1: Tornado Climatology and Near-Surface Wind Characteristics
ROOM: ASCE/CHS2M Hill
WSC Moderator: Frank Lombardo, Ph.D., EIT, A.M.ASCE; University of Illinois
WSC Scribe: Zach Wienhoff; Haag Engineering Company
One of the first steps in assessing the societal impact of tornadoes is to understand and quantify the tornado hazard. The session will examine engineering-relevant properties of the tornado hazard and what information is needed to improve future versions of ASCE/SEI 7-22 and fundamental research. These properties include (1) those associated with tornado climatology such as tornado frequency, path length/width, maximum intensity, and the spatial distribution of wind speeds typically collected from post-tornado damage assessment and (2) the high-resolution, four-dimensional characteristics of tornadoes such as wind profiles, the vertical component of the velocity, spatiotemporal variations and evolution, influences of topography and terrain, and atmospheric pressure changes. The breakout group will coordinate with the loading group for a clearer description of the engineering-relevant properties needed in subsequent steps to determine tornado impacts.
Reading Material:
a.
ASCE/SEI 7-22 Chapter 32 (Special note of the design load parameters)
Tornado Wind Speed Maps for Building Design: Research and Development of Tornado Risk Assessment Methodology, NIST Technical Note Tornado Wind Speed Maps for Building Design: Research and Development of Tornado Risk Assessment Methodology | NIST
In this session we will make recommendations for the research required to improve the (GCp)’s currently required for use in tornado design in ASCE/SEI 7-22 and how to specify these values. We will be considering components and cladding, main wind force resisting system loads, windborne debris, and internal pressure including the effects of the pressure drop within a tornado. We must address how the relative structure-tornado size is considered in the standard, considering that the tornado wind speed maps depend on the area of the structure and provide the maximum wind speed anywhere on the structure.
Reading Material:
a.
Haan Jr., F. L., V. K. Balaramudu, and P. P. Sarkar. 2010. “Tornado-induced wind loads on a low-rise building.” J. Struct. Eng. 106–116.
b.
Kopp, G. A., and M. J. Morrison. 2011. “Discussion of 'tornado-induced wind loads on a low-rise building’ by F. L. Haan Jr., Vasanth Kumar Balaramudu, and P. P. Sarkar.” J. Struct. Eng. 1620–1629.
Additional Reading Material (Not Provided):
a.
Haan Jr., F. L. 2017. “An examination of static pressure and duration effects on tornado-induced peak pressures on a low-rise building.” Front. Built Environ. 1–11.
b.
Haan Jr., F. L., P. P. Sarkar, and W. A. Gallus. 2008. “Design, construction and performance of a large tornado simulator for wind engineering applications.” Eng. Struct. 30: 1146–1159.
Breakout Session Topic 3: Design of Residential Structures
ROOM: Seabury & Smith
WSC Moderator: John van de Lindt, Ph.D., F.SEI, F.ASCE; Professor, Colorado State University
WSC Scribe: Blythe Johnston, S.M.ASCE; Colorado State University
This session will examine current practices in residential construction (one- and two-family dwellings) as defined by the IRC and will review case studies in what some cities in tornado-prone regions are now requiring for residential construction. Topics will include connections, glazing requirements, debris considerations, overall resiliency, residential shelters, and cost efficiency. The goals of the session are to define current state-of-the-art practices and then prioritize research and development needs specifically for residential construction and the possible avenues for implementing the results over the next decade.
Reading Material:
a.
Prevatt, D. O., J. W. van de Lindt, E. W. Back, A. J. Graettinger, et al. 2012. “Making the case for improved structural design: The tornado outbreaks of 2011.” J. Leadership Manage. Eng. 12 (4), 254–270. Making the Case for Improved Structural Design: Tornado Outbreaks of 2011 | Leadership and Management in Engineering | Vol 12, No 4 (ascelibrary.org)
b.
van de Lindt, J. W., S. Pei, T. N. Dao, A. Graettinger, et al. 2013. “Dual objective-based tornado design philosophy.” J. Struct. Eng. 139 (2): 251–263. Dual-Objective-Based Tornado Design Philosophy | Journal of Structural Engineering | Vol 139, No 2 (ascelibrary.org)
c.
Standohar-Alfano, C. D., J. W. van de Lindt, and B. R. Ellingwood. 2017. “Vertical load path failure risk analysis of residential wood-frame construction in tornadoes.” J. Struct. Eng. 143(7): 04017045. Vertical Load Path Failure Risk Analysis of Residential Wood-Frame Construction in Tornadoes | Journal of Structural Engineering | Vol 143, No 7 (ascelibrary.org)
d.
Ramseyer, C., L. Holliday, and R. Floyd. 2015. “Enhanced residential building code for tornado safety.” J. Perform. Constr. Facil. 30 (4) Enhanced Residential Building Code for Tornado Safety | Journal of Performance of Constructed Facilities | Vol 30, No 4 (ascelibrary.org). https://doi.org/10.1061/(ASCE)CF.1943-5509.0000832.
Breakout Session Topic 4: Design Using ASCE/SEI 7-22
ROOM: Cardinal
WSC Moderator: Cherylyn Henry, P.E., F.SEI, F.ASCE, ZAPATA Group, Inc.
WSC Scribe: Korah Parackal, Ph.D., CPEng, A.M.ASCE; Insurance Institute for Business & Home Safety
This session will examine buildings designed using ASCE/SEI 7-22. Discussion will include input and feedback from practitioners currently using the ASCE/SEI 7-22 tornado provisions in design practice. The other focus will be inclusion of RC II structures in the provisions of the next revision of ASCE/SEI 7. The goal of the session will be to define and prioritize research and development needs for making any changes needed to the existing provisions and including RC II structures in ASCE/SEI 7-22.
Reading Material:
a.
ASCE/SEI 7-22, Chapter 32
b.
ASCE/SEI 7-16, Commentary Chapter 26
c.
FEMA/NIST Design Guide for New Tornado Load Requirements in ASCE/SEI 7-22 Design Guide for New Tornado Load Requirements in ASCE 7-22 | FEMA.gov
Breakout Session Topic 5: Design of Tornado Shelters and Safe Rooms
ROOM: Harris
WSC Moderator: Marc Levitan, Ph.D., F.SEI, M.ASCE; Lead Research Engineer, NWIRP, NIST
WSC Scribe: Shane Crawford, Ph.D., A.M.ASCE; University of Alabama
Life safety protection from intense tornadoes is provided by tornado shelters and tornado safe rooms (FEMA terminology for shelters). In this session we will review the current state of the art of design of tornado shelters. We will then identify and prioritize research needs in topic areas including but not limited to shelter design-level tornado hazards, including debris; tornado loads, load cases, and load combinations; material and product impact and pressure testing methods and standards; and design strategies and solutions for new construction and retrofits.
Reading Material:
a.
FEMA P-361 (2021a)
b.
FEMA P-320 (2021b) Taking Shelter from the Storm - Building or Installing a Safe Room for Your Home (fema.gov)
c.
ASCE/SEI 7-22, Chapter 32 and commentary on tornado loads
Additional Reading Material (Not Provided):
a.
ICC 500 (2023) Storm Shelter Standard 2020 ICC 500 ICC/NSSA Standard for the Design and Construction of Storm Shelters - CHAPTER 1 (iccsafe.org)
Breakout Session Topic 6: Tornado Effects on Non-building Structures and Beyond ASCE/SEI 7-22
ROOM: Waddell
WSC Moderator: Alex Griffin, P.E., S.E., M.ASCE; Burns & McDonnell
WSC Scribe: John Haney, A.M.ASCE; Burns & McDonnell
Community resiliency includes traditional building structures and the infrastructure supporting them. This includes the power, nuclear, industrial, electric, solar, and telecommunication industries. This breakout session will focus on the current state of knowledge for these industries and identify the research needed to better understand and design these structures and systems against tornado loads.
Reading Material:
a.
ASCE/SEI 7-22, Chapter 32 and commentary
b.
ASCE Manual of Practice 74, Appendix K Guidelines for Electrical Transmission Line Structural Loading | Books (ascelibrary.org)
c.
NRC Regulatory Guide 1.76 Revision 1 of Regulatory Guide 1.76, “Design-Basis Tornado and Tornado Missiles for Nuclear Power Plants” (Formerly Draft Regulatory Guide DG-1143). (nrc.gov)
d.
“The Impacts to Structure Design when Considering Load Cases in Excess of NESC 250B, 250C, and 250D” (T-line economics study)
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