Multi-hazard design is a potentially powerful means to achieve structures that meet the requirement of risk consistency with respect to safety metrics, and may be synergistic through the use of design features appropriate for one hazard that enhance performance with respect to another hazard. The project develops procedures for achieving designs that are safe, sustainable, and economical under multiple hazards. It supports these procedures with novel tools for accurate characterization of the effects of wind hazards (wind speeds and windborne debris), aerodynamic loading, storm surge and wave effects due to hurricanes, and structural response to these effects under single and combined hazards. These tools include modern statistical methods, including highly efficient Extreme Value estimation methods, data compression for Database Assisted Design, and Computational Wind Engineering methods based on the NIST Fire Dynamics Simulator software as adapted for bluff body aerodynamics calculations.
Objective: To develop by 2016 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, tornadoes, storm surge and waves, in a multi-hazard context.
What is the new technical idea? Use the capabilities of numerical computation, existing data, and spatial statistics to develop new procedures that describe wind and storm-surge loads and effects, including combined effects, with superior accuracy and for any mean recurrence interval that will be required for the development of the ASCE 7-16 Standard or other standards. An improved description will help reduce losses and waste of materials and achieve more efficient structures. This goal requires:
- developing realistic wind maps to replace the current, statistically incorrect ASCE 7-10 Standard maps, via
- mining and use of NOAA ASOS wind data, and
- innovative multi-hazard modeling of wind speed extremes in mixed wind climates (e.g., climates with thunderstorm, synoptic, and/or tropical storm winds);
- tools for tornado hazard characterization and probability-based tornado hazard map; and
- methodology for performance-based tornado-resistant design for ordinary buildings subject to tornado hazards (extreme wind speeds and windborne debris).
A science-based methodology for aerodynamic measurements can be developed to eliminate the gross errors revealed by inter-laboratory comparisons of pressures. Such a methodology is to be validated in NIST’s new converted and equipped boundary layer wind tunnel that will soon be operational. Finally, progress in the adaptation of the Fire Dynamics Simulator will be pursued with a view to create software capable of simulating the aerodynamic response of bluff bodies immersed in atmospheric flows. For storm surge, an integrative, interdisciplinary methodology will be developed that
- 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 effects;
- 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
- 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:
- novel prediction methods for extreme speeds in mixed climates (multi-wind-hazard) regions (completed in 2010);
- full capabilities for mining relevant NOAA data and simulating large sets of multi-directional wind speed data (completed in 2011);
- non-directional wind map for ASCE Standard (pre-standard, 2014);
- probability distributions of hurricane wind speeds determined for structural reliability investigation purposes (2014), and
- directional wind speed databases (software , 2015).
Aerodynamic databases: In view of limitations of current aerodynamic databases,
- expand aerodynamic databases available to designers by verifying Tokyo Polytechnic University databases (largest databases in the world) against validated UWO data (2014), and
- improve upon Database-Assisted Design procedures accepted by ASCE 7 Standard to facilitate their widespread use (2014).
Computational Wind Engineering (CWE):
- perform and attempt validation of numerical calculations for low-rise buildings (2013);
- use wind tunnel results to validate CWE results (2014), and
- use available full-scale measurement results to validate CWE results (2015).
Tornado resilient design:
- perform comprehensive review and statistical analysis of existing tornado databases (2014);
- develop proposed tornado hazard maps (2015); and
- in collaboration with appropriate stakeholders, develop risk-consistent performance-based tornado design methodology to ensure that the performance of all components and systems that make up a building meet the same performance objective when subject to tornado hazards (2016).
Storm Surge: methodology for
- hydrodynamic simulation (with no waves) and derivation of design criteria for three representative Florida basins (completed in 2009); and
- incorporation of wave model (SWAN) into SLOSH model and pilot hydrodynamic simulation for one representative basin sensitive to wave effects (completed in 2010);
- in coordination with relevant agencies and stakeholders hold interagency workshop on methodology, with stakeholders and other agencies (2014);
- feasibility study for expansion of applicability of the NIST methodologies developed for Florida pilot regions, for entire Gulf and Atlantic coasts, and
- 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 (2015).
- Yeo, D. (2013). “Generation of Large Directional Wind Speed Datasets for Estimation of Wind Effects with Long Return Periods”, Journal of Structural Engineering, ASCE, in review.
- Dunn, C.L., Friedland, C.J., and Levitan, M.L., (2013). “Statistical representation of design parameters for hurricane risk reduction of structures”, Structural Safety, in review.
Potential Research Impacts:
- Gabbai, R. and Simiu, F., (2013). “Evaluation of Mean Recurrence Intervals of Wind Effects for Tall Building Design”, Journal of Structural Engineering, ASCE, in press.
- Simiu, E., Letchford, C., Isyumov, N., Chowdhury, A.G., and Yeo, D, (2013). “An Assessment of ASCE 7-10 Standard Methods for Determining Wind Loads”, Journal of Structural Engineering, ASCE, in press.
- Yeo, D. and Potra, F., (2013). “Sustainable Design of Reinforced Concrete Structures through CO2 Emission Optimization”, Journal of Structural Engineering, ASCE.
- Yeo, D., Lin, N., and Simiu, E. (2013). “Estimation of Hurricane Wind Speed Probabilities: Application to New York City and Other Coastal Locations,” Journal of Structural Engineering, ASCE.
Realized Research Impacts:
- Yeo, D., (2013). “Multiple Points in Time Estimation of Peak Wind Effects on Structures”, Journal of Structural Engineering, ASCE, 139, 462-471.
- Fu, T.C., Aly, A.M., Chowdhury, A.G., Bitsuamlak, G., Yeo, D. and Simiu, E. (2012). “A Proposed Technique for Determining Aerodynamic Pressures on Residential Structures,” Wind and Structures, 15 (1).
- Lombardo, F.T., (2012). “Improved extreme wind speed estimation for wind engineering applications,” Journal of Wind Engineering and Industrial Aerodynamics, Volumes 104–106, Pages 278–284.
- Yeo, D. and Simiu, E., “High-Rise Reinforced Concrete Structures: Database-Assisted Design for Wind,” Journal of Structural Engineering, ASCE.
- Crosti, C., Duthinh, D., and Simiu, E., “Risk-consistency and synergy in multi-hazard design,” Journal of Structural Engineering, ASCE.
- Coffman, B., Main, J., Duthinh, D., and Simiu, E., (2010). “Wind Effects on Low-Rise Metal Buildings: Database-Assisted Design vs. ASCE 7-05 Standard Estimates,” Journal of Structural Engineering, ASCE.
- Duthinh, D., and Simiu, E., (2010). “Safety of Structures in Strong Winds and Earthquakes: Multihazard Considerations,” Journal of Structural Engineering, ASCE.
- Simiu, E., Gabbai, R.D., Fritz, W.P., “Wind-induced tall building response: a time domain approach,” Wind and Structures, 11, 427-440.
- Lombardo, F.T., Main, J.A., and Simiu, E. (2009) “Automated Extraction and Classification of Thunderstorm and Non-Thunderstorm Wind Data for Extreme-Value Analysis,” Journal of Wind Engineering and Industrial Aerodynamics, 97(3-4), 120-131.
- Fritz, W.P., B. Bienkiewicz, B. Cui, O. Flamand, T. C. E. Ho, H. Kikitsu, C. W. Letchford, and E. Simiu , “International Comparison of Wind Tunnel Estimates of Wind Effects on Low-Rise Buildings: Test-Related Uncertainties,” Journal of Structural Engineering, ASCE, 134 87-90.
Impact of Standards and Tools:
- Proposals submitted to the ASCE 7 Standard on combined wind and storm surge, combined wind and seismic loads, database assisted design, and the wind tunnel method. (FY13)
- New hurricane shelter design wind speed map submitted to and accepted by the ICC 500 Storm Shelter Standard committee. Updated draft standard will be released for public comment soon. (FY13)
- Database Assisted Design for Tall Reinforced Concrete Buildings software tools. (Posted online in FY11)
- Technical Basis for Regulatory Guidance on Design-Basis Hurricane-Borne Missile Speeds for Nuclear Power Plants, issued as NUREG/CR-7004, U.S. Nuclear Regulatory Commission. (Published in FY12)
October 1, 2011
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