The importance of strong-motion data in engineering seismology and earthquake engineering

1. The importance of strong-motion data in engineering seismology and earthquake engineering Roberto PAOLUCCI Department of StructuralEngineering Politecnico di Milano, ITALY

2. Outline Influence of strong motion processing on numerical simulations of soil-structure interaction problems Selection of real accelerograms based on displacement-spectrum compatibility

3. Influence of strong motion processing on numerical simulations of soil-structure interaction problems • A benchmark problem • Seismic response analysis of a diaphragm wall (Foti and Paolucci, 2012)

4. Influence of strong motion processing on numerical simulations of soil-structure interaction problems Selection of input records for non-linear time-history analyses Corrected acceleration time histories from: 1) European Strong Motion Database 2) ITalian ACelerometric Archive 3) PEER strong motion database

5. Influence of strong motion processing on numerical simulations of soil-structure interaction problems ATINA NS record

6. Influence of strong motion processing on numerical simulations of soil-structure interaction problems ATINA NS record ITACA “pad-strip” procedure to safely remove zero-padding and ensure compatibility of SM records tapering + detrend on displacements

7. Influence of strong motion processing on numerical simulations of soil-structure interaction problems

8. Atina Influence of strong motion processing on numerical simulations of soil-structure interaction problems

9. Bagnoli Influence of strong motion processing on numerical simulations of soil-structure interaction problems

10. Influence of strong motion processing on numerical simulations of soil-structure interaction problems • Displacement time histories at top of the wall – Atina record

11. Influence of strong motion processing on numerical simulations of soil-structure interaction problems peak values of displacement and bending moment – Atina record

12. Bagnoli Influence of strong motion processing on numerical simulations of soil-structure interaction problems Atina

13. Influence of strong motion processing on numerical simulations of soil-structure interaction problems • Summary • Consequences of processing procedure • Limited on bending moments • Relevant (20-30%) on displacements (important for PBD) • Differences observed on a relatively rigid system (conservative design with PS approach of EC8). Likely higher effects on more flexible systems • “Engineering” rules to avoid gross errors in the use of real accelerograms used as input motion for non-linear dynamic soil-structure interaction analyses: • do not manipulate the corrected record provided by the database; • prefer records corrected by acausal filtering; • prefer digital records; • check, before the numerical simulation, that velocities and displacements resulting by integration of the input acceleration are not affected by unphysical drifts.

14. Outline Influence of strong motion processing on numerical simulations of soil-structure interaction problems Selection of real accelerograms based on displacement-spectrum compatibility

15. Selection of real accelerograms based on displacement-spectrum compatibility • Introductory works at Politecnico from 2000 to 2010, for characterization of long period ground motion • displacement spectra at long periods (→ Faccioli et al., 2004) • Study on the reliability of long period spectral ordinates from digital accelerograms(→ Paolucci et al., 2008) • GMPE at long periods (→ Cauzzi and Faccioli, 2008) • PSHA at long periods for Italian sites (→ Faccioli and Villani, 2009)

16. Reliability of long-period response spectral ordinates from digital accelerograms Morge Sep 8, 2005 Pennine Alps (MW4.4, Re=17 km) Zihuatanejo Jan 11, 1997 Michoacán (MW7.1, Re=143 km) After Paolucci et al., 2008 "the elastic spectra from the most basic processing, in which only the pre-event mean is removed from the acceleration time series, do not diverge from the baseline-corrected spectra until periods of 10–20 sec (...) Akkar and Boore (2009)

17. Probabilistic seismic hazard studies in Italy • 17 SeismicHazardMap of Italy (0 – 2 s) DPC-INGV Project S1 – 2005-2007 http://esse1.mi.ingv.it

18. Probabilistic seismic hazard studies in Italy • 18 Long period PSHA in Italy: maps of D10 DPC-INGV Project S5 – 2005-2007 Faccioli and Villani, 2009

19. Probabilistic seismic hazard studies in Italy • 19 Long period PSHA in Italy: map of TD

20. Probabilistic seismic hazard studies in Italy • 20 How to match short and long period PSHA results and put them in a format for engineeringapplications ? → towards a target displacementspectrum for Italiansites (TDSI)

21. Selection of real accelerograms based on displacement-spectrum compatibility Joint research activity of Politecnico di Milano & Università Federico II Napoli Target displacementspectra for Italiansites SIMBAD: a database for engineering analyses of long period ground motion Software REXEL-DISP v 1.1 Examples of application

22. A Target Displacement Spectrum for Italian Sites Broadband displacementspectrum for design, matching the Italian NTC08 regulationsat short periods with the long period PSHA D10,TD from Project S5, while ag, , S, Cc, F0, TC, TE, TF come from NTC08 : factor introduced to match short and long periods (=1 for constant velocity) F: long period site factor (from S5 project)

23. A Target Displacement Spectrum for Italian Sites Italian norms NTC08 Long period PSHA Connecting branch T-α

24. A Target Displacement Spectrum for Italian Sites  = 0.85 -1.4

25. A Target Displacement Spectrum for Italian Sites Comparison of TDSI with NTC08 (Italianseismicregulations) TDSI NTC08 A: VS30 = 800 m/s; B: VS30 = 580 m/s; C/E: VS30 = 270 m/s; D: VS30 = 140 m/s

26. A Target Displacement Spectrum for Italian Sites Site factors NTC08 TDSI

27. Selection of real accelerograms based on displacement-spectrum compatibility Target displacementspectra for Italiansites SIMBAD: a database for engineering analyses of long period ground motion Software REXEL-DISP v 1.1 Examples of application

28. SIMBAD: Selected Input Motions for displacement-Based Assessment and Design • 32 Worldwide regions EC8 Site classes

29. Selection of real accelerograms based on displacement-spectrum compatibility Target displacementspectra for Italiansites SIMBAD: a database for engineering analyses of long period ground motion Software REXEL-DISP v 1.1 Examples of application

30. 34 Software REXEL-DISP v 1.1 (www.reluis.it) available at http://www.reluis.it

31. Selection of real accelerograms based on displacement-spectrum compatibility Target displacementspectra for Italiansites SIMBAD: a database for engineering analyses of long period ground motion Software REXEL-DISP v 1.1 Examples of application

32. Examples of application • 36 Dependence on the target spectrum (NTC08 vs TDSI) Aquila, TR = 475 years

33. Examples of application • 37 Dependence on seismicity level (Aquila vs Udine, TR = 475 yr, TDSI)

34. Examples of application • 38 Broadband compatibility (Aquila, TR = 475 years, TDSI)

35. Practical hints for using REXEL-DISP

36. 40 Concluding remarks • Whyusingspectraldisplacementsas a target for groundmotionselection? • the target magnituderangeis “naturally” satisfied; • no need to scale accelerograms; • a broadband spectralcompatibilityiseasilyachieved (→ NLTHA of MDOF systems – non-linear dynamic SSI – soilstabilityproblems) • ... but ... • the accelerogramsshould be selected from high-quality strong-motiondatabases, covering the seismichazardlevels and site conditions of interest; • the target spectrumshould be carefullydefinedbased on seismichazardstudiesat long periods

37. Thank you !