New Generation Seismic Codes and New Technologies in Earthquake Engineering 26-27 Februray 2015 – Ankara, Turkey

Revised Probabilistic Seismic Hazard Map of Turkey and Its Implications in Seismic Design Sinan Akkar Boğaziçi University Kandilli Observatory and Earthquake Research Institute 34684 Çengelköy İstanbul

Outline • Revised Turkish seismic hazard map • Observations for design ground-motion definition • • • • •

Comparisons of old and new design spectral ordinates Damping scaling factors Long-period spectral corner period (TL) Vertical-to-horizontal spectral ratios Near-fault effects

Sinan Akkar

Revision of Turkish seismic hazard map project S. Akkar, T. Eroğlu Azak, T. Çan, U. Çeken, M.B. Demircioğlu, T. Duman, S. Ergintav, T.F. Kadirioğlu, D. Kalafat, Ö. Kale, R.F. Kartal, T. Kılıç, S. Özalp, K. Şeşetyan, S. Tekin, A. Yakut, M.T. Yılmaz, M. Utkucu, Ö. Zülfikar

A multi-institutional project funded by the Disaster and Emergency Management Presidency (AFAD) and Turkish Catastrophe Insurance Pool (TCIP)

Sinan Akkar

• Revise seismic hazard maps at the national level based on the recent state-of-the-art developments and findings in this field (Turkey and worldwide) • Provide spectral ordinates (PGA, SA at T = 0.2s and 1.0s) for return periods of 43 years (69%/50 years), 72 years (50%/50 years), 475 years (10%/50 years) and 2475 years (2%/50 years) for their use in the definition of updated code spectra and insurance premiums • Provide additional information on vertical-tohorizontal spectral ordinate ratios, long-period corner period, damping scaling factors and forward directivity effects Sinan Akkar

Earthquake Catalog • Compilation of instrumental catalog (12674 earthquakes) is based on national / international catalogs • Historical catalog (512 earthquakes) is compiled from the recently finished GEM-Historical Catalog, SHARE and EMME projects • Minimum magnitude bound is 4 • Homogenized magnitudes (Mw) through empirical conversion equations developed from the compiled catalog • Declustering and completness analyses

Sinan Akkar

Seismic Sources Active faults in mainland Turkey

Area sources in and around mainland Turkey

553 fault segments Active faults around mainland Turkey

200 km buffer zone

Literature review, already finished national and international projects, earthquake catalogs, GIS maps to determine active fault segments, area sources, maximum magnitudes, slip rates, geometries, style-of-faulting, depth distribution etc. Sinan Akkar

AREA SOURCE (AS)

SOURCE CHARACTERIZATION FAULT + BACKGROUND (FS)

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SHALLOW ACTIVE CRUSTAL SEISMICITY

GROUND-MOTION CHARACTERIZATION INTERFACE AND INSLAB SEISMICITY

Akkar et al. (2014) – 0.3 Akkar and Çağnan (2014) – 0.3 Chiou and Youngs (2008) – 0.3 Zhao et al. (2006) – 0.1

Zhao et al. (2006) – 0.4 Lin and Lee (2008) – 0.2 Atkinson and Boore (2003) – 0.2 Youngs et al. (2006) – 0.2

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• Compute hazard for each seismic source model considering the GMPEs and seismic source logic-trees. • Combine the results with alternative source model weights SAat at 0.2s –475 475 yrs (10% in 50 yrs) SA 1.0s yrs (10% 50 yrs) PGA ––475 yrs (10% inin 50 yrs)

Sinan Akkar

Current Turkish design spectrum Site Classes

TA

Proposed Turkish design spectrum TB

Design: 10% probability of exceedance in 50 yearsSA (T=R A= 475 S(T) yrs) 0

For TR = 475 yrs (10%/50) Immediate Occupancy, Increase by 50% for TR = Life Safety and yrs (2%/50). Reduce Collapse2475 Prevention performances: 50% by 50% for TR = 72 yrs (50%/50) probability of exceedance in 50 years

= 8s

Earthquake Zone

to 2%

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Comparisons of design ground motion İzmir Bursa Ataşehir - İstanbul

2.5 2.5 2.5

Bursa İzmir Ataşehir - İstanbul

140 140 140

• New maps generally yield smaller seismic demands • Spectral shape provided in TEC 2007 results in large differences in the longperiod range Antalya Antalya Maslak -Eskişehir İstanbul • Ad-hoc 1.5 factor to scale 2475-year Maslak -Eskişehir İstanbul spectrum from 475-year spectrum is not realistic. Scaling between 2475-year and 475-year spectra depends on the seismic activity of the region 2.0 2.0 2.0 1.5 1.5 1.5

1.0 1.0 1.0 0.5 0.5 0.5

TEC07 TEC07- -10%/50yrs -10%/50yrs 10%/50yrs TEC07 TEC07 2%/50yrs TEC07 2%/50yrs TEC07 - 2%/50yrs New Map New Map -10%/50yrs 10%/50yrs New Map- -10%/50yrs New Map 2%/50yrs New Map 2%/50yrs New Map - 2%/50yrs

120 120 120

Spectral Displacement(cm) (cm) Spectral Spectral Displacement Displacement (cm)

Spectral Acceleration(g) (g) Spectral Spectral Acceleration Acceleration (g)

TEC07 TEC07- -10%/50yrs -10%/50yrs 10%/50yrs TEC07 TEC07 TEC07- -2%/50yrs -2%/50yrs 2%/50yrs TEC07 New NewMap Map- -10%/50yrs -10%/50yrs 10%/50yrs New Map New Map - 2%/50yrs New Map 2%/50yrs New Map - 2%/50yrs

100 100 100 80 80 80 60 60 60 40 40 40 20 20 20

0.0 0.0 0.0

000

111

2.5 2.5 2.5

222 333 Period Period(s) (s) Period (s)

444

555

SpectralAcceleration Acceleration (g) Spectral Spectral Acceleration(g) (g)

TEC07 - 10%/50yrs TEC07 TEC07--10%/50yrs 10%/50yrs TEC07 - 2%/50yrs TEC07 TEC07--2%/50yrs 2%/50yrs New Map- 10%/50yrs - 10%/50yrs New NewMap Map - 10%/50yrs NewMap Map--2%/50yrs -2%/50yrs 2%/50yrs New New Map

2.0 2.0 2.0 1.5 1.5 1.5 1.0 1.0 1.0 0.5 0.5 0.5 0.0 0.0 0.0

000

111

222 333 Period(s) (s) Period Period (s)

444

555

000

140 140 140

111

222 333 Period Period(s) (s) Period (s)

444

555

444

555

TEC07--10%/50yrs -10%/50yrs 10%/50yrs TEC07 TEC07 TEC07- 2%/50yrs - 2%/50yrs TEC07 TEC07 - 2%/50yrs NewMap Map--10%/50yrs -10%/50yrs 10%/50yrs New New Map NewMap Map- 2%/50yrs - 2%/50yrs New New Map - 2%/50yrs

120 120 120

SpectralDisplacement Displacement (cm) Spectral Spectral Displacement(cm) (cm)

000

100 100 100 80 80 80 60 60 60 40 40 40 20 20 20

000

000

111

222 333 Period(s) (s) Period Period (s)

Sinan Akkar

Spectral ratio distribution between 2475year and 475-year spectral ordinates SA@T=0.2s TR475 /TR475 SA@T=1.0s PGA – TR2475–/TR 2475 2475 475

Spectral ratio between 2475-year and 475-year spectral ordinates varies between 1.6 and 3.5. It increases towards seismically less active regions

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Dependency of SA2475/SA475 on seismic activity may indicate… Performance assessment for collapse prevention: [(Seismic Demand)2475/(Seismic Demand)475]high seismicity

< [(Seismic Demand)2475/(Seismic Demand)475]low seismicity

For collapse prevention performance assessment: Buildings located in highly seismic regions will be subjected to lesser seismic demands than those located in low-seismicity regions with respect to their design strength capacities. Sinan Akkar

Moreover… The exceedance probabilities of ground motions (spectral accelerations) do not consider the uncertainties in the seismic behavior of structures (structural capacity). Thus, the next step in code-based work should be the definition of design ground motions for a uniform risk according to the performance objective: risk-targeted adjustment of ground motions

fcapacity (c) = capacity probability density function P(SA > c) = annual probability of SA > c

Risk Fragility Hazard Sinan Akkar

Damping scaling factors (DSFs) currently expressed as predictive models in terms of magnitude, source-to-site distance, site conditions, faulting style etc)

Requires simplifications for their effective use in the codes Sinan Akkar

DSFs for x = 1% for different magnitudes and distances M5.5, V VS30 = 255 255 m/s, m/s, SS, SS, xx == 1% 1% M7.5, S30 = M6.5, S30

222

No significant differences in DSF variation for different distances

111

0.5 0.5 0.5 000 0.01 0.01 0.01

0.1 0.1 0.1

111

10 10 10

Period (s) Period Period (s) (s) 5.5, 1, 255 7.5, 6.5, 1, 1, 255 255 5.5, 20, 255 7.5, 6.5, 20, 20, 255 255

5.5, 5, 255 7.5, 6.5, 5, 5, 255 255 5.5, 30, 255 7.5, 6.5, 30, 30, 255 255

5.5, 10, 10, 255 255 7.5, 6.5, 10, 255 5.5, 40, 40, 255 255 7.5, 6.5, 40, 255

5.5, 50, 255 7.5, 6.5, 50, 50, 255 255

5.5, 75, 255 7.5, 6.5, 75, 75, 255 255

5.5, 100, 100, 255 255 7.5, 6.5, 100, 255

x = 1%

2

Magnitude dependency of DSFs can also be averaged out for their implementation to the codes

1.5

DSF

DSF DSF DSF

1.5 1.5 1.5

1

0.5 0 0.01

0.1

1

10

Period (s) M5.5

M6.5

M7.5

Average

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Period (s) 2

x = 1%

x = 3%

x = 7%

x = 20%

x = 30%

x = 50%

x = 10%

DSF

1.5 1 0.5 0 0.01

0.1

1

10

Period (s) x = 1%

x = 3%

x = 7%

x = 20%

x = 30%

x = 50%

x = 10%

1% 3% 7% 10% 20% 30% 50%

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Horizontal-to-vertical spectrum ratio Vertical spectrum should be consistent with the horizontal spectrum

Develop the vertical spectrum from the already defined horizontal spectrum

Behavior of vertical spectrum is different than the horizontal spectrum: The vertical constant acceleration plateau is shorter than its horizontal counterpart

Short-period corner period as well as the decaying branch is sensitive to the variations in the short-period vertical spectral ordinates and long-period horizontal spectral ordinates

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• Compute Sav,0.1s and Sav,1.0s from Sah,0.2s and Sah,1.0s: 1.0

0.6

SA Sav,1.0s (g)(g) vertical,T1s

0.8 SA Savertical,max v,0.1s (g)(g)

Empirical expressions developed from many earthquake scenarios

0.20

-1

0.4 0.2 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 SAhorizontal,max (g) Sah,0.2s (g)

0.15 0.10

SAv=a*SAhb a b

0.05 0.00 0.00

0.10

0.20 0.30 0.40 SA Sahorizontal,T1s (g) (g)

-1

T=0.2s 0.6682 1.0897

T=1s 0.4681 0.9609

0.50

h,1.0s

-1

• Define Cv and CL from computed Sav,0.1s and Sav,1.0s as well as from Sah,0.2s: T Vertical DS T n 0V

CL describes the width of const. acc. plateau and slope of decaying branch in vertical spectrum

CL ≥ 0.80 0.75 ≤ CL < 0.80

SV

0.05 0.15 0.90 0.05 0.17 0.85

0.60 ≤ CL < 0.70

0.05 0.20 0.80 0.05 0.25 0.75

0.50 ≤ CL < 0.60

0.05 0.30 0.70

CL < 0.50

0.05 0.30 0.60

0.70 ≤ CL < 0.75

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Spectral Acceleration Spektral ivme

Long-period spectral corner period

Acc.

TTA0 TSB

Vel.

Disp.

TTLL

Important for long-period structures that are more sensitive to deformation demands

Important remark: Large magnitude events are richer in long-period groundmotion components. Thus, TL is sensitive to magnitude:

TL  Magnitude Sinan Akkar

Near-fault (forward directivity) Rupture velocity  Particle shear wave velocity

Most of the seismic energy arrives in a short-duration waveform with a large amplitude single pulse

Long-duration waveform with low amplitudes

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Implementation to design-based spectra – 475 years

30 km @ 5 km

Prob. dist. of Sa considering the occurrence and non-occurrence of pulse-like ground motion

Prob. dist. of m, r, tp

Pattern used to investigate the influence of forward directivity on code-based design spectrum Fault with different rupture lengths and slip rates to mimic seismic activity

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Implementation to design-based spectra – 2475 years In terms of period, slip rate and Mchar

Amp2475/Amp475 regions

Determine the regions where simplified factors apply Factor 3

Ry/L

Simplification

Factor 2

Factor 1

Rx/L

Spectra with NF effects Sinan Akkar

Success of the proposed model for NF effects

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Conclusive remarks • Revision of Turkish seismic hazard map project will be the basis of new design spectrum • The project helped to do many important observations and findings for engineering use • Many more can be done… • These observations can be elaborated further for their use in the definition of design ground motion in the new Turkish code

Sinan Akkar

Thank you

Sinan Akkar