further development of site response in nga models
DESCRIPTION
Further Development of Site Response in NGA Models. PEER Lifelines Program NGA-West2 Project Topic #8 Working Group Meeting. Kickoff Meeting. April 20, 2010. Agenda. 10 am: Welcome/logistics (Stewart/Bozorgnia) 10:10 am: NGA-West2 overview and project objectives (Bozorgnia) - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/1.jpg)
Further Development of Site Response in
NGA Models
PEER Lifelines ProgramNGA-West2 Project
Topic #8
Working Group Meeting
Kickoff Meeting April 20, 2010
![Page 2: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/2.jpg)
Agenda
• 10 am: Welcome/logistics (Stewart/Bozorgnia)• 10:10 am: NGA-West2 overview and project objectives
(Bozorgnia)• 10:30 am: Background on NEHRP site factors (Borcherdt)• 11:00 am: Results from previous NGA Site Factor Working
Group (Power)• 11:30 am: Comparison of NGA-West site terms to NEHRP
(Stewart/Seyhan)• Noon: Lunch• 1 pm: Open discussion of project objectives, scope,
deliverables, & schedule
![Page 3: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/3.jpg)
Project Management
• Yousef Bozorgnia, PEER, NGA-West2 Project Manager
• Jonathan P. Stewart, UC Los Angeles (Working Group Chair)
• Emel Seyhan, UC Los Angeles (GSR)
![Page 4: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/4.jpg)
Working Group Committee (WGC)• Don Anderson, CH2MHill, Bellevue, WA (Geotechnical engineer, TS3 Member) • Roger Borcherdt, USGS, Menlo Park, CA (Engineering seismology, developer
of NEHRP site factors)• C. B. Crouse, URS Corporation, Seattle, WA (Geotechnical engineer, TS3 Chair
and PUC Member)• R.W. Graves, URS, Pasadena, CA (Seismologist, ground motion simulation and
basin effects)• I.M. Idriss, UC Davis, Santa Fe, NM (Geotechnical engineer, GMPE developer)• Maury Power, AMEC Geomatrix, Oakland, CA (Geotechnical engineer, for TS3
Chair) • Walter Silva, PEA, El Cerrito, CA (Seismologist, NGA database manager, GMPE
developer) • Thomas Shantz, Caltrans, Sacrament, CA (Geotechnical engineer)
![Page 5: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/5.jpg)
• Do we need others?
Working Group Committee (WGC)
![Page 6: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/6.jpg)
• Database provided by NGA-West2 (PEA)• Technical work by UCLA researchers• Oversight of work direction/results by WGC• Oversight of WGC by …?• Deliverables:
– Check of NGA-W models (trends with Vs30, nonlinearity, sigma)
– Evaluate basin depth effects– Develop technical basis for, and consensus behind, revisions
to NEHRP site factors
Logistics
![Page 7: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/7.jpg)
Agenda
• 10 am: Welcome/logistics (Stewart/Bozorgnia)• 10:10 am: NGA-West2 overview and project objectives
(Bozorgnia)• 10:30 am: Background on NEHRP site factors (Borcherdt)• 11:00 am: Results from previous NGA Site Factor Working
Group (Power)• 11:30 am: Comparison of NGA-West site terms to NEHRP
(Stewart/Seyhan)• Noon: Lunch• 1 pm: Open discussion of project objectives, scope,
deliverables, & schedule
![Page 8: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/8.jpg)
NGA-West2 Overview and Project Objectives
Yousef Bozorgnia
![Page 9: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/9.jpg)
Background on NEHRP Site Factors
Roger Borcherdt
![Page 10: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/10.jpg)
Results from Previous NGA Site Factor Working Group
Maury Power
![Page 11: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/11.jpg)
Agenda
• 10 am: Welcome/logistics (Stewart/Bozorgnia)• 10:10 am: NGA-West2 overview and project objectives
(Bozorgnia)• 10:30 am: Background on NEHRP site factors (Borcherdt)• 11:00 am: Results from previous NGA Site Factor Working
Group (Power)• 11:30 am: Comparison of NGA-West site terms to NEHRP
(Stewart/Seyhan)• Noon: Lunch• 1 pm: Open discussion of project objectives, scope,
deliverables, & schedule
![Page 12: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/12.jpg)
Outline
• Evaluation of Site Factors– Available approaches– Approaches adopted in NEHRP and NGA
GMPEs– Input parameters
• Comparison of NGA & NEHRP site terms
![Page 13: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/13.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D
Vs
InputRock Att.
G/GMax
D
Output
![Page 14: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/14.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D
Day et al. 2008
![Page 15: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/15.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D– Randomized soil
properties and input motions (1D only)
Walling et al. 2008
![Page 16: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/16.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D– Randomized soil
properties and input motions (1D only)
Walling et al. 2008
![Page 17: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/17.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D– Randomized soil
properties and input motions (1D only)
– Site factors from simulation results
Walling et al. 2008
![Page 18: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/18.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D– Randomized soil
properties and input motions (1D only)
– Site factors from simulation results
Day et al. 2008
![Page 19: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/19.jpg)
Evaluation of Site Factors
• Simulation driven: – Computational model,
1D or 3D– Randomized soil
properties and input motions (1D only)
– Site factors from simulation results
Day et al. 2008
![Page 20: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/20.jpg)
Evaluation of Site Factors
• Simulation driven: – Not used as “stand alone” factors for active regions– Used to constrain certain aspects of “hybrid” models
![Page 21: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/21.jpg)
Evaluation of Site Factors
• Simulation driven• Empirical (reference
site approach) – Single event– IMsoil/IMref: evaluate
dependence on site condition and PGAref
Borcherdt 2002
![Page 22: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/22.jpg)
Evaluation of Site Factors
• Simulation driven• Empirical (reference site
approach) • Empirical (non-reference
site approach)– Multiple events– Analysis of residuals– Evaluate dependence on
site condition, PGArock, etc.
Choi & Stewart 2005
![Page 23: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/23.jpg)
Evaluation of Site Factors
SimulationEmpirical:Ref. Site
Empirical:Non-Ref. Site
![Page 24: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/24.jpg)
Evaluation of Site Factors
SimulationEmpirical:Ref. Site
Empirical:Non-Ref. Site
NEHRP Factors
Nonlinearity Weak Motion Amplification
![Page 25: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/25.jpg)
Evaluation of Site Factors
SimulationEmpirical:Ref. Site
Empirical:Non-Ref. Site
NGA: AS, CB
NonlinearityAmplification
level; Vs30-dependence
![Page 26: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/26.jpg)
Evaluation of Site Factors
SimulationEmpirical:Ref. Site
Empirical:Non-Ref. Site
NGA: BA, CY
Nonlinearity; Amplification
level; Vs30-dependence
![Page 27: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/27.jpg)
Evaluation of Site Factors
• Input parameters:– NEHRP: Vs30, Ss, S1
– AS: VS30, Median PGA1100
– BA: VS30, Median PGA760
– CB: VS30, Median PGA1100
– CY: VS30, Median + i (Sa)1130
![Page 28: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/28.jpg)
NGA-NEHRP Comparisons
• In natural log units, site term = Fx(Vs30, Ax)– Fx=amplification relative to Vs30=x site condition
– Ax=ground motion amplitude for reference site condition of Vs30=x
• Use Vs30=150, 270, 560, 760, and 1100 m/s• Evaluate F at T=0.3 and 1.0 sec.
![Page 29: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/29.jpg)
NGA-NEHRP Comparisons
• Ax:– A=median PGA for AS, BA, CB – A=Sa at period of interest for CY (median + i);
Take Sa(0.3)=2.5×PGA and Sa(1.0)=1.0×PGA
• Adopt reference condition of 760 m/s– F760(Vs30, Ax)=Fx(Vs30, Ax)-Fx(760, Ax)
xxxsxa
xa
xa
Vsa
a
Vsa AFAVFS
S
S
S
S
S,760,exp 30
760
30
760
30
![Page 30: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/30.jpg)
NEHRP E D C B B
![Page 31: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/31.jpg)
Suggestions on NEHRP-NGA comparisons
• Average Sa across all NGA periods in the ranges for Fa and Fv. Use average of logs + limits. Exact middle of the range too (e.g. 0.3 sec for Fa, 1.2 sec for Fv)
• Average across velocities in site class: use wt average based on histograms of Vs30.
• Ask Brian how he plotted F vs PGA
• Check coding using full models.
• Check NGA errata for AS
![Page 32: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/32.jpg)
Residuals Analysis• WS: run NGA for 760 with NEHRP factors and look
at residuals. – All sites and estimates Vs only
• Use GMRotI50
• New data: – Use June 2010 version of NGA flat file
– Alan Yong, USGS: he has funding to perform site investigations. His site list has been approved, previous efforts to provide input on sites to investigate have been resisted
![Page 33: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/33.jpg)
Residuals Analysis
• New data: – Residuals analysis, including Baja earthquake
data, focusing on low Vs30 range.
![Page 34: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/34.jpg)
Other recommendations
• USGS maps for all Vs30s, with interpolation (next generation of mapping)
• When we have the new factors, compare hybrid predictions with them & old factors with full psha for various sites in Nor Cal and So Cal.
• Check sites without Vs using Virtual Geotechnical Data Center (TS will send url and password).
• Google earth file with CA stations, see where E stations are (look at other categories too).
![Page 35: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/35.jpg)
NGA-NEHRP Comparisons
Differences:• NEHRP Fv high
– Esp for C to E• NEHRP nonlinearity
stronger for C to D• NEHRP Fa and Fv high
for rock (Class B)
![Page 36: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/36.jpg)
Working Group Objectives & Scope
![Page 37: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/37.jpg)
Objectives
• Input to NGA-West2 developers• Develop technical basis for, and consensus
behind, revisions to NEHRP site factors– Problems with medians– Different sigmas
![Page 38: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/38.jpg)
![Page 39: Further Development of Site Response in NGA Models](https://reader036.vdocument.in/reader036/viewer/2022062305/56815b64550346895dc95260/html5/thumbnails/39.jpg)
Task Order Scope• Database