1. The importance of strong-motion data in engineering seismology and earthquake engineering
Roberto PAOLUCCI
Department of Structural Engineering
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. Selection of input records for non-linear time-history analyses
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. Influence of strong motion processing on numerical simulations of soil-structure interaction problems
Atina

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

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

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. displacement spectra at long periods (→ Faccioli et al., 2004)
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. Seismic Hazard Map of Italy (0 – 2 s)
Probabilistic seismic hazard studies in Italy 17
Seismic Hazard Map of Italy (0 – 2 s)
DPC-INGV Project S1 – 17

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

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

20. → towards a target displacement spectrum for Italian sites (TDSI)
Probabilistic seismic hazard studies in Italy 20
How to match short and long period PSHA results and put them in a format for engineering applications ?
→ towards a target displacement spectrum for Italian sites (TDSI) 20

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

22. F: long period site factor (from S5 project)
A Target Displacement Spectrum for Italian Sites
Broadband displacement spectrum for design, matching the Italian NTC08 regulations at 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
 =

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

26. Comparison of TDSI with NTC08 (Italian seismic regulations)
A Target Displacement Spectrum for Italian Sites
Comparison of TDSI with NTC08 (Italian seismic regulations)
Site class A
TDSI
NTC08
TDSI

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

28. Comparison of TDSI with NTC08 (Italian seismic regulations)
A Target Displacement Spectrum for Italian Sites
Comparison of TDSI with NTC08 (Italian seismic regulations)
Aquila - SLV
Udine - SLV

29. A Target Displacement Spectrum for Italian Sites
Comparison of long period response spectral ordinates from different seismic regulations (NTC08, EC8, ASCE 7-10, NZS1170)
- site class B (NTC08, EC8) or C (NZS1170, ASCE 7-05)

30. Displacement spectrum Range of variability of TD
A Target Displacement Spectrum for Italian Sites 30
Displacement spectrum
Range of variability of TD
EC8
1.2 s for M < 5.5
2.0 s for M > 5.5
NTC08
Ranging from about 1.8 s (for ag/g = 0.05) to 2.8 s (for ag/g = 0.30)
NZS
3.0 s
ASCE 7-05
Ranging from about 4 s (for M = ) to 16 s (for M = )
TDSI
3.7 s median value,   = 1.4 s
after SIMBAD database

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

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

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

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

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

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

37. Examples of application37
Dependence on seismicity level
(Aquila vs Udine, TR = 475 yr, TDSI)

38. Examples of application38
Broadband compatibility
(Aquila, TR = 475 years, TDSI)

39. Type of application Hints
Practical hints for using REXEL-DISP
Type of application
Hints
Search for 7 one- or two-component displacement-spectrum compatible accelerograms
- preference to unscaled records
- use of wide magnitude and distance intervals (e.g., default values: 5-7 and 0-30 km) and any site class (due to the limited number of records on some soil types in the SIMBAD database)
- ensure spectral matching over a rather broad range of vibration periods (e.g., default values: s)
- when searching for scaled records the use of limited magnitude and distance range is found to be more feasible.
Search for displacement-spectrum compatible individual records
- use of wide magnitude and distance intervals (e.g., default values: 5-7 and 0-30 km) and any site class
- limit spectral compatibility to relatively small period ranges (e.g., 1-3 s)
Search for 30 displacement-spectrum compatible accelerograms
- preference to unscaled records when selecting 30 one-component records but the use of scale factors is advisable when searching for 30 two-component records.
- use of wide magnitude intervals (e.g., default values: 5-7) and any site class

40. the target magnitude range is “naturally” satisfied;
Concluding remarks 40
Why using spectral displacements as a target for ground motion selection?
the target magnitude range is “naturally” satisfied;
no need to scale accelerograms;
a broadband spectral compatibility is easily achieved (→ NLTHA of MDOF systems – non-linear dynamic SSI – soil stability problems)
... but ...
the accelerograms should be selected from high-quality strong-motion databases, covering the seismic hazard levels and site conditions of interest;
the target spectrum should be carefully defined based on seismic hazard studies at long periods

41. Thank you !