P17 SDC* Working Group Meeting 3

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1 P17 SDC* Working Group Meeting 3 *Seismic Design Category Julie C. Furr, PE, SECB Senior Engineer CSA Engineering, Inc. P17 SDC Working Group

2 Outline Welcome Member Update and Introductions P17 Update from 11/2016 Meeting SDC Definitions SDC Map Options April Workshop Proposed Approach Open Discussion

3 Working Group Members Core Group Julie Furr (TN) Bob Pekelnicky (CA) Jim Harris (CO) Bill Holmes (CA) Jon Siu (WA) Ben Enfield (WA) Paul Timko (AR) CSA Engineering, Inc Degenkolb Engineers James Harris & Associates Rutherford & Chekene City of Seattle, WA City of Seattle, WA Cromwell Architects & Engineers

4 Working Group Members Support Group Philip Schneider BSSC (Executive Director) Ronald O. Hamburger Simpson Gumpertz & Heger (P17 Chair) Jiqiu Yuan BSSC Mai Tong FEMA Bob Hanson Technical Advisor to FEMA

5 P17 Meeting Update SDC Definitions => Issue Team-01 SDC Map Options => SDC Working Group Member Reponses to Questions from last meeting April Workshop (04/11/2017, 10 am - 5 pm) Preferred risk basis for seismic design value maps Preferred approach to designation of Seismic Design Categories

6 Working Group Questions 1. Apparent SDC Working Group Direction: Agree or Disagree? a. Remove structure considerations from the definition of SDC, such that the new RSH definition reflects only geological considerations independent of building construction type and occupancy. i. Structure considerations are not proposed to be eliminated, but would be moved to the other side of the equation after basic SDC/RSH is determined. b. RSH will define a baseline of minimum requirements in a particular geographic region, for all structures, based solely on the geologic hazard. i. Additional requirements can be imposed for higher risk structures, but shall not be reduced below the baseline for lower risk structures. c. RSH would define hazard regions in terms of relative national seismic hazard as opposed to absolute hazard based on numerical ground motion values.

7 Working Group Questions 2. Should site class be included in RSH maps or not? Why or why not? a. If site class should not be included, how could it be accounted for downstream in the design process? b. To adjust RSH based on site class opens up the possibility of gaming the system to achieve a lower seismic category such as happened in Denver. Alternately, site class cannot just be ignored

8 Working Group Questions 3. What do you perceive as potential impacts within your particular field? Positive? Negative? a. Please identify your field along with pros, cons, expected objections, and other information as you feel relevant. 4. To define map boundaries: 2. Mark Petersen, Nico, and Sanaz have proposed to use a compilation of contours from the last several map versions to generate our starting RSH map. This would remain fairly static unless compelling scientific information comes to light that would justify changing the boundaries. Model tweaks and modifications would not automatically result in boundary adjustments. 3. Do we keep the current 5 categories (A-E)? Do we expand to more? Less? 4. Do you support or oppose using municipal boundaries of some type (county, city, etc)?

9 Proposed Approach W.G.

10 Proposed Approach 1. Start with USGS Hazard Model Values 2. Normalize to Reference City 3. Average Normalized values 4. Divide into equal sized bins 5. Assign cities to bins 6. Compare city hazard based on assigned bin

11 Proposed Approach USGS Hazard Model Values Uniform Hazard 2% in 50 years B-C Boundary values => Site Class B Not risk targeted No deterministic capping Versions Used: 2014, 2008, values are also available but are on a 0.1-degree grid Did not have time to interpolate for this meeting Recommend these be included for comparison

12 Proposed Approach Normalize to Reference City San Francisco Average 2014, 2008, 2002 normalized values Divide into equal sized bins Assign Cities to bins 5 bins => 14 cities varied 4 bins => 7 cities varied All variations were by 1 bin, between 1.0s and 0.2s Compare bin assignments between Reference Cities

13 1.0s San Francisco 1.8 RELATIVE USGS HAZARD MODEL VALUES 1.0S NORMALIZED TO SAN FRANCISCO Atlanta Boston Charleston Chicago Dallas Memphis New York St. Louis Washington, DC Concord Monterey Oakland Sacramento San Francisco San Jose San Mateo Santa Cruz Santa Rosa Vallejo Boise Denver Las Vegas Reno Salt Lake City Everett Portland Seattle Tacoma s s s Average SFO 1.0 Century City Irvine Long Beach Los Angeles Northridge Riverside San Bernardino San Diego San Luis Obispo Santa Barbara Ventura

14 0.2s San Francisco 1.8 RELATIVE USGS HAZARD MODEL VALUES 0.2 SEC NORMALIZED TO SAN FRANCISO Atlanta Boston Charleston Chicago Dallas Memphis New York St. Louis Washington, DC Concord Monterey Oakland Sacramento San Francisco San Jose San Mateo Santa Cruz Santa Rosa Vallejo Boise Denver Las Vegas Reno Salt Lake City Everett Portland Seattle Tacoma Century City Irvine Long Beach Los Angeles Northridge Riverside San Bernardino San Diego San Luis Obispo Santa Barbara Ventura s s s Average SFO 0.2

15 RELATIVE USGS HAZARD MODEL VALUES 1.0s San Francisco s San Francisco

16 Results Based on 2002, 2008, 2014 USGS Hazard Models L1=>L4/L5, Lowest => Highest ASCE 7-10 SDC Provided for comparison Site Class B

17 RELATIVE HAZARD 5 BINS L1 L2 L3 L4 L5 (A-C) (D) (D) (D) (D) Atlanta Everett Charleston Century City Concord Boise Memphis Irvine Los Angeles Oakland Boston Portland Long Beach Northridge San Bernardino Chicago San Luis Obispo Monterey San Francisco Santa Barbara Dallas Reno San Jose Santa Rosa Denver Riverside San Mateo Las Vegas Salt Lake City Vallejo New York San Diego Ventura Sacramento St.Louis Washington, DC Santa Cruz Seattle Tacoma NOTES Based on 2002, 2008, 2014 USGS Hazard Models L1=>L5, Lowest => Highest ASCE 7-10 SDC Site Class B

18 RELATIVE HAZARD 4 BINS L1 L2 L3 L4 (A-C) (D) (D) (D) Atlanta Charleston Century City Concord Boise Everett Long Beach Oakland Boston Irvine Los Angeles San Bernardino Chicago Memphis Northridge San Mateo Dallas Monterey Reno Santa Barbara Denver Portland Riverside Santa Rosa Las Vegas San Luis Obispo Salt Lake City Ventura New York Seattle San Diego Sacramento Tacoma San Francisco St. Louis San Jose Washington, DC Santa Cruz Vallejo NOTES Based on 2002, 2008, 2014 USGS Hazard Models L1=>L4, Lowest => Highest ASCE 7-10 SDC Site Class B

19 Things to Consider... Current Seismic Design Categories SDC A-C falls within Level 1 in all cases SDC D covers Level 2 and above Define seismic and non-seismic regions? Non-seismic regions to be subdivided based on hazard level? Site Class Will make a significant difference in some cities St. Louis per ASCE 7-10 SDC B based on Site Class B SDC C based on Site Class D and Sds SDC D based on Site Class D and Sd1

20 Still Need to Address... Boundary definition This approach leads back to contours. Site Class Include in this process or not? Risk Targeting If not in acceleration values, where do we include this? Deterministic Capping Is this still necessary with this approach? Risk Category Keep this in ASCE 7 to further restrict allowed systems Would this eliminate Category I? Face-to-Face Meeting: ?

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