ASCE/SEI 7-22 Minimum Design Loads for Buildings and …

1 Comments Submitted by the ASCE 7 Flood Load Technical Committee in response to the FEMA Public Comment Period on the National Flood Insurance Program's Minimum Floodplain Management Standards. Member Location Company Andre Barbosa, , OR Oregon State University Graham Brasic , FL Jezerinac Group Chris Cerino, NY STV Inc. Bill Coulbourne, MD Coulbourne Consulting Dan Cox (chair), OR Oregon State University Matthew Gilbertson, , OR Simpson Gumpertz and Heger Carol Friedland , LA Louisiana State University Tori Johnson, MD US Naval Academy Chris Jones, NC Consulting Richard Lo, TX Langan Engineering Jessica Mandrick, , NY Gilsanz Murray Steficek Jeff Melby MS USACE. Mehedi Rashid, , MD Moffatt & Nichol Seth Thomas, , OR KPFF Consulting Peter Willse, CT Willse Engineering The american society of civil Engineers Standard ASCE/SEI 7-22 Minimum Design Loads for Buildings and Other Structures incorporates a chapter on flood loading, Chapter 5.

2 The ASCE 7. Flood Load Technical Committee is responsible for this chapter and is currently working on a supplement which will propose determining flood Loads based on flood mean recurrence intervals (MRI) that are higher than the National Flood Insurance Program (NFIP) 100-year standard for most building structures. Our committee has found that the flood Loads presently derived from the Base Flood ( , 100- year flood or 1% annual probability of exceedance flood), do not meet the reliability targets of the ASCE 7 standard. Wind events, which often occur concurrently with coastal floods, utilize mean recurrence intervals of 300, 700, 1700, and 3000-years for Risk Category I-IV structures respectively.

3 The Loads resulting from 100-year flood events are not proportional to the wind events that are at these higher recurrence intervals. Previous editions of ASCE 7 have tried to increase the reliability by applying a load factor of two on flood Loads in coastal regions subject to wave action. This scaling factor increased the magnitude of the flood Loads for structures within coastal high hazard areas but did not increase the depth over which the load was applied or the geographic area where the flood load would be considered. This reduced the effectiveness of the load factor approach. Our committee is proposing a supplement to ASCE 7 to increase the geographic area subject to flood provisions of the standard from the 100-year floodplain to the 500-year floodplain.

4 We also propose utilizing MRI flood elevations corresponding to the importance of a structure: a 100- year MRI flood elevation would be used for Risk Category I Structures (structures with a low risk to human life in the event of failure); a 500-year MRI flood elevation for Risk Category II. Structures (most residential and commercial structures); and a 750-year and 1,000-year MRI. flood elevation for Risk Category III and IV Structures, respectively (critical structures with the highest risk to human life in the event of failure). In accordance with these proposals, we believe that the 100-year flood is not an appropriate basis for the Design for most structures. As only loading is within the purview of this standard, we are providing the loading based on the flood elevation and cannot mandate building floor elevations or construction standards.

5 We encourage FEMA to adopt the following: utilize a risk-based approach to floodplain management standards;. utilize the 500-year flood as the basis for Design of Risk Category II Buildings and set building elevation requirements above the 500-year flood elevation;. utilize floods higher than the 500-year flood for Risk Category III and IV essential and critical Buildings ;. utilize the 500-year floodplain as the regulatory flood hazard area;. incorporate future conditions, such as climate change effects, into regulatory floodplain designations and building standards;. utilize the 500-year flood as the basis of Design for single and multi-family homes built in accordance with the International Residential Code (IRC).

6 The IRC does not adopt ASCE 7 for Loads . Single family homes and other IRC structures suffer large flood related losses, and increasing the MRI flood for these structures will reduce those losses. We appreciate FEMA's willingness to accept public comments on the National Flood Insurance Program's Minimum Floodplain Management Standards, and we look forward to developing consistencies between ASCE's Minimum standards for flood Loads and FEMA's Minimum requirements for floodplain management to minimize flood damage and loss.