Wind Engineering and Multi-Hazard Failure Analysis Project

Multi-hazard design is a potentially powerful means to achieve structures that meet the requirement of risk consistency with respect to safety metrics, as well as being synergistic through the use of design features appropriate for one hazard that enhance performance with respect to another hazard. The project develops procedures that utilize optimization methods for achieving designs that are safe and economical under multiple hazards constraints, and supports these procedures with novel tools for accurately determining wind speeds, aerodynamic behavior, storm surge and wave effects due to hurricane winds, and structural response to these hazards.

Objective:  To develop by 2014 next-generation methods, tools, and maps to better characterize wind and storm surge hazards to enable performance-based standards for designing structures to resist extreme winds, including hurricanes and tornadoes, and storm surge in a multi-hazard context.

What is the new technical idea?  The fundamental new technical idea is to use the capabilities of numerical computation, existing data, and spatial statistics, to develop new procedures and standard provisions that describe wind and storm-surge loads and effects with superior accuracy. An improved description will provide the basis for design approaches that will reduce losses and achieve more efficient structures. This goal requires developing:

1. realistic wind maps to replace the current, statistically incorrect, ASCE 7 Standard maps, via
2. 1. mining and use of NOAA ASOS wind data, and
   2. innovative multi-hazard modeling of wind speed extremes in mixed wind climates (e.g., climates with thunderstorm and synoptic winds or tropical storms);
3. science-based methodologies for aerodynamic simulation and measurements to eliminate the gross errors revealed by international comparisons of wind tunnel estimates; and
4. tools for tornado hazard characterization and probability-based tornado hazard maps. For storm surge, an integrative, interdisciplinary methodology will be developed that
5. 1. utilizes a probabilistic approach to storm track selection for hydrodynamic simulation thereby allowing for calculation of site-dependent mean recurrence intervals (MRIs) of any joint wind speed/surge height events;
   2. enables incorporation of the wave model (SWAN, Simulating WAves Nearshore) into SLOSH model (Sea, Lake, and Overland Surges from Hurricanes) to account for wave action in addition to total inundation; and
   3. provides data/validation for use as the basis for design criteria for structures in coastal regions.

What is the research plan?   The research plan covers the following:

Wind climatology:

1. novel prediction methods for extreme speeds in mixed climates (multi-wind-hazard) regions (completed in 2010);
2. full capabilities for mining relevant NOAA data and simulating large sets of multi-directional wind speed data (completed in 2011);
3. non-directional wind map for ASCE Standard (pre-standard, 2013);
4. directional wind speed databases (pre-standard, 2013); and
5. probability distributions of hurricane wind speeds determined for structural reliability investigation purposes (2013).

Pilot Computational Wind Engineering (CWE):

1. perform and attempt validation of numerical calculations for low-rise buildings (2013); and
2. use wind tunnel results to validate CWE results, and use CWE results to develop wind tunnel simulation capabilities (2014).

Tornado resilient design:

1. perform comprehensive review and statistical analysis of existing tornado databases (2013); and
2. develop proposed tornado hazard maps (2014).

Storm Surge: methodology for

1. hydrodynamic simulation (with no waves) and derivation of design criteria for three representative Florida basins (completed in 2009);
   
2. incorporation of wave model (SWAN) into SLOSH model and pilot hydrodynamic simulation for one representative basin sensitive to wave effects (completed in 2010);
3. in coordination with National Science and Technology Council Subcommittee on Disaster Reduction, hold interagency workshop on methodology, with stakeholders and other agencies (2014);
4. feasibility study for expansion of applicability of the NIST methodologies developed for Florida pilot regions, for entire Gulf and Atlantic coasts; and
5. draft methodology for use in development of design criteria for the combined effects of wind speed,storm surge and wave hazards for structures in hurricane prone regions (2014).
   

Recent Results:

Impacts:

• NIST report to the Nuclear Regulatory Commission published as NUREG/CR-7004 Technical Basis for Regulatory Guidance on Design-Basis Hurricane-Borne Missile Speeds for Nuclear Power Plants (2011).
• Incorporation in ASCE 7-10 Standard of major contributions by NIST, including
• • Database-Assisted Design techniques
  • Correlation between Saffir/Simpson scale and ASCE 7-10 Standard basic speeds;
  • Requirements pertaining to directional wind climatological/aerodynamics interface.

Outcomes:

• Proposed change to ASCE 7-16 standard to identify limitations of current analytical methods for determination of wind loads, as documented in several NIST publications (2012).
• Completed development and documentation of software, Database Assisted Design for Tall Reinforced Concrete Buildings,  www.nist.gov/wind (2011).  Developed database-assisted design procedures with the capability to substantially improve modeling of wind effects on both low- and high-rise structures.
• Developed a methodology for estimating the risk posed by the combined effect of hurricane wind and storm surge on specific coastal location, accounting for local topography (2009).
• Developed a methodology for incorporating effects of waves on total storm surge calculation using NOAA’s SLOSH model (2010).
• Developed map-based software tool for extracting joint probabilities of combined hurricane wind speed and storm surge hazards for the Tampa Bay and Fort Myer basins (2010)

Outputs:

Publications:

Lombardo, F.T., Pintar, A., Possolo, A., and Simiu, E., “Meteorological Extremes,” Encyclopedia of Environmetrics (accepted for publication).

Yeo, D.., “Multiple Points-In-Time Estimation of Peak Wind Effects on Structures,” J. Struct. Eng., (accepted for publication).

Yeo, D., “Practical Estimation of Veering Effects on High-Rise Structures: A Database-Assisted Design Approach.” Wind and Structures (accepted.for publication).

Yeo, D. and Jones, N.P., “Aerodynamic Forces Induced by Vertically Oscillating Incoming Flow on a Yawed Horizontal Circular Cylinder.” Journal of Wind Engineering & Industrial Aerodynamics (in press).

Lombardo, F.T. “Improved extreme wind speed estimation for wind engineering applications”. Journal of Wind Engineering & Industrial Aerodynamics, Available online 31 March 2012 (in press).

Simiu, E., Lombardo, F., and Yeo, D., “Ultimate Wind Load Design Gust Speeds in the U.S.” (Discussion), J. Struct. Eng., Vol. 138, No. 5, May 2012, 660-661.

Fu, T.C. et al., “A Proposed Technique for Determining Aerodynamic Pressures on Residential Homes,” Wind and Structures, Vol. 15, No. 1 (2012) 27-41.

Simiu, E. et al., Testing of Residential Homes under Wind Loads. ASCE Natural Hazards Review, Vol. 12, 2011, 166-170.

Yeo, D. and Simiu, E., “High-Rise Reinforced Concrete Structures: Database-Assisted Design for Wind.” J. Struct. Eng., Vol. 137, No. 11, Nov. 2011, 1340-1340.

Yeo, D. and Jones, N.P., “Computational Study on Aerodynamic Mitigation of Wind-Induced, Large-Amplitude Vibrations of Stay Cables with Strakes.” Journal of Wind Engineering & Industrial Aerodynamics, 99(4), pp.389-399, 2011.

NIST Reports:

Levitan, M.L., Kuligowsli, E.D., Lombardo, F.T., Phan, L.T., and Jorgensen, D.P., Progress Report National Institute of Standards and Technology (NIST); Technical Investigation of the May 22, 2011, Tornado in Joplin, Missouri NISTSP 1139, November 2012.

Levitan, M.L., Phan, L.T., Kuligowsli, E.D., Lombardo, F.T., and Jorgensen, D.P., Investigation Plan, National Institute of Standards and Technology (NIST) Technical Investigation of the Joplin, Missouri, Tornado of May 22, 2011 NIST SP1132, May 2012.

Simiu, E. et al., An Assessment of Methods for Determining Wind Loads, NIST Tech. Note 1738, Feb., 2012.

Yeo, D., Database-Assisted Design for Wind: Multiple Points-in-Time Approach. NIST Tech. Note 1711, National Institute of Standards and Technology, 2011.

Conference papers/presentations:

Phan, L.T.; Slinn, D.N., Kline, S.W., “Wave Effects on Hurricane Storm Surge Simulation,” accepted for ATC-SEI Advances in Hurricane Engineering — Learning from Our Past, October 24-26, 2012, Miami, Florida.

Yeo, D. and Simiu, E., “Structural Reliability of Tall Buildings under Wind Loads: Estimation of Sampling Errors in the Estimation of the Response.” the 2012 Structures Congress, Chicago,  Mar. 29-31, 2012. (Best Poster Award)

Fu, T.C., Aly, A.M., Chowdhury, A.G., Bitsuamlak, G., Yeo, D., and Simiu, E., “Simplified Wind Flow and Aerodynamic Response of Residential Homes: Laboratory and Computational Fluid Dynamics Simulations.” Proceedings of the Forth International Conference on Experimental Vibration Analysis for Civil Engineering Structures, p.193-199, Varenna, Italy, Oct. 3-5, 2011.

Phan, L.T. and Simiu, E.; “Estimation of risk for design of structures exposed to combined effects of hurricane wind speed and storm surge hazards,” ICASP11, Applications of Statistics and Probability in Civil Engineering, Faber, Köhler, and Nishijima (eds), 2011 Taylor & Francis Group, London, ISBN 978-0-415-66986-3.

Standards and Codes:

The ASCE/SEI 7 Standard (Minimum Design Loads on Buildings and Other Structures) is the primary U.S. standard for wind and flood loading on buildings and structures.  ASCE/SEI 7 is adopted by reference in the International Building Code (IBC) and the International Residential Code (IRC), which are the model codes used by most jurisdictions in the country that enforce building codes.  Therefore, ASCE/SEI 7 is the main emphasis of the standards strategy for this project.

The ASCE/SEI 7 Standard began a a new revision cycle in spring 2012 (next edition will be ASCE/SEI 7-16).  NIST will work in collaboration with other experts in the field to develop and submit changes proposals for the standard by 2014 for new wind speed maps and to improve: (1) requirements and procedures for the wind tunnel method; (2) methods for determining wind loads accounting for combined wind and seismic hazards; and (3) handling of joint probabilities of wind speeds and storm surge.

Current standards committee participation by project members include: ASCE/SEI 7 Wind Load Subcommittee (Simiu, distinguished member); ASCE/SEI 7 Subcommittee on Flood Loads (Phan, member); ASCE/SEI 7 Subcommittee on Tsunami Loads (Phan, member); ASCE/SEI 37 Design Loads on Structures During Construction (Simiu, member).; American Nuclear Soc. Standard ANS 2.3, Standard for Estimating Tornado, Hurricane, and Straight Winds (Simiu, member).