Interreg IIIB: SISMOVALP WP6: Generic alpine ground motion
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Interreg IIIB: SISMOVALP WP6: Generic alpine ground motion A 2D Simulation benchmark for the A 2D Simulation benchmark for the study of the seismic response of study of the seismic response of alpine valley alpine valley Sismovalp Meeting, Martigny, Switzerland, October 2-4
description
Interreg IIIB: SISMOVALP WP6: Generic alpine ground motion. A 2D Simulation benchmark for the study of the seismic response of alpine valley. Sismovalp Meeting, Martigny, Switzerland, October 2-4. Participants to the 2D Benchmark. Geometry of the valley. W = 4050 m H = 450 m - PowerPoint PPT Presentation
Transcript of Interreg IIIB: SISMOVALP WP6: Generic alpine ground motion
Interreg IIIB: SISMOVALP
WP6: Generic alpine ground motion
A 2D Simulation benchmark for the A 2D Simulation benchmark for the study of the seismic response of study of the seismic response of
alpine valleyalpine valley
Sismovalp Meeting, Martigny, Switzerland, October 2-4
Participants to the 2D Benchmark
# Partner Participants Model Data 2D Methods 3D Methods
1 UJF-LGIT (Grenoble)
Chaljub Grenoble Valley 2D Spectral Element 3D Spectral Element
2 POLIMI (Milano) Paolucci Val D’Adige (Trento)
P-SV: Spectral Element Method
3D Spectral Element
3 UDST-DST(Trieste)
Suhadolc, Vaccari, Panza, Costa
Val Resia and Gemona
SH + P-SV: Hybrid FD – Modal Summation
4 INOGS(Trieste/Udine)
Priolo, Laurenzano
Tagliamento River High Valley (Tolmezzo)
SH + P-SV: Chebyshev Spectral Element
3D Pseudo-Spectral Staggered Fourier
5 ETH (Zurich) Faeh, Alvarez-Rubio
Valais Valley P-SV: Direct Boundary Element
3D Direct Boundary Element 3D Finite Difference
6 UNITN (Trento) Kaser P-SV: ADER-DG (no attenuation)
SISMOVALP PROJECT – 3nd annual meeting, Milano 15-16 September 2005
Geometry of the valley
W = 4050 mH = 450 mShape ratio: H/(0.5*W)= 0.22
Model 0 (M0)
Stratigraphic layout Units H (m)
VS
(m/s)
Vp (m/s)
VP/VS (kg/m3)
QS Qp
Recent Deposits Sandy Gravel 0-15 250 500 2.5 1600 20 40
Fine Deposits Silt & clay 15-30 350 700 2.5 1700 20 40
Fluvial & Lacustrine Deposits
Silt, clay and gravel
30-100 450 900 2.5 1800 30 50
Fluvial & Lacustrine Deposits
Silt, clay and gravel
100-350 600 1200 2.5 1900 30 50
Moraine = 350-450 800 1600 2 2000 50 100
Bedrock Limestone 450- 2800 5200 1.85 2500 200 400
Model 1 (M1)
Stratigraphic layout Units H (m)
VS
(m/s)
Vp (m/s)
VP/VS (kg/m3)
QS Qp
Recent Deposits Sandy Gravel 0-15 250 500 2.5 1600 20 40
Fine Deposits Saturated Silt & clay
15-30 350 1650 2.5 1700 20 40
Fluvial & Lacustrine Deposits
Silt, clay and gravel
30-100 450 900 2.5 1800 30 50
Fluvial & Lacustrine Deposits
Silt, clay and gravel
100-350 600 1200 2.5 1900 30 50
Moraine = 350-450 800 1600 2 2000 50 100
Bedrock Limestone 450- 2800 5200 1.85 2500 200 400
Model 2 (M2)
Stratigraphic layout Units H (m)
VS
(m/s)
Vp (m/s)
VP/VS (kg/m3)
QS Qp
Fluvial & Lacustrine Deposits
Silt, clay and gravel
0-450 260 + 30 z1/2
525 + 60 z1/2
2 1600 + 59.5 z1/3
20 + 1.64 z1/2
40 + 3.3 z1/2
BedrockBedrock Limestone 450- 2800 5200 1.85 2500 200 400
2D benchmark
Simul. #
Model Incidence Angle
UJF POLIMI UNITS OGS ETH UNITN Simul. #
P-SV P-SV P-SVSH
P-SVSH
P-SV P-SV
1 M0 0 1
2 M0 -30 2
3 M0 30 3
4 M1 0 4
5 M1 -30 5
6 M1 30 6
7 M2 0 7
8 M2 -30 8
9 M2 30 9
Synthetic seismograms
Synthetic seismogramsComputed at the two reference receivers for simulation 2
They represent the input motion, to some extent
Left side Right side
Response Spectrum Spectra Ratios (RSSR)Angle=0
LGIT POLIMI
INOGS ETH
UNITN
Response Spectrum Spectra Ratios (RSSR)Angle=30
LGIT POLIMI
INOGS ETH
UNITS UNITN
Response Spectrum Spectral Ratios (RSSR)
Different models and incidence angles
Response Spectrum Spectral Ratios (RSSR)
Different models and incidence angles
Different models and incidence angles
Response Spectrum Spectral Ratios (RSSR)
Variation (%) due to incidence angle
Response Spectrum Spectral Ratios (RSSR)
Comparison of the methods for simulations 1 and 2
Response Spectrum Spectral Ratios (RSSR)
Comparison of the methods for simulations 2 and 3
Response Spectrum Spectral Ratios (RSSR)
1D transfer function(Wavenumber Integration Method, Herrmann, 2004)
Angle=0
Angle=-30
Source time function
LGIT POLIMI
INOGS ETH
UNITS UNITN
2D transfer functions
No attenuation
LGIT POLIMI
INOGS ETH
UNITN
2D vs. 1D transfer functions
1 2 3
1 2 3
Simulation 1
Simulation 2
Simulation 3
2D transfer functions
1 2 3
1 2 3LGIT
POLIMI
INOGS
ETH
Aggravation Factor
No attenuationAggravation Factor = SA2D / SA1D
u1D = STF * TF1D
LGIT POLIMI
INOGS ETH
UNITN
Aggravation Factor
Aggravation Factor
2D Benchmark
Status
• All synthetics have been computed. • Results have been analysed;• Conclusions are presently under discussion;• A scientific report will be delivered within the final report;• A paper will be prepared.
2D Benchmark – Preliminary conclusions
Evaluated features
Importance
RSSR AF
Vs fine details Low Low
Incidence angle Medium High
Numerical method Low Medium(???)
Spectral frequency Low MediumIn this benchmark, both valley shape and 1D reference layering were held fixed.
The valley shape-ratio is mainly 1D.
WP6 – Priority features
Element Importance
Shape (1D, 2D, 3D) and depth High
Main impedance contrast
(e.g. bedrock/sediments)
High
Vs average profile Medium-high
Shallow Vs (30-50 m) Medium-high
Numerical method Medium(-low)
Details of the valley shape Medium-low
Detailed Vs profile Low
Spectral variability of the amplification ????
Priority list of elements which must be investigated in order to assess
the seismic response of an alpine valley:
WP6 – Priority features
Element Importance How to assess them?
Shape (1D, 2D, 3D) and depth High ?
Main impedance contrast
(e.g. bedrock/sediments)
High ?
Vs average profile Medium-high ?
Shallow Vs (30-50 m) Medium-high ?
Numerical method Medium(-low) ?
Details of the valley shape Medium-low ?
Detailed Vs profile Low ?
Spectral variability of the amplification ???? ?
Priority list of elements which must be investigated in order to assess
the seismic response of an alpine valley:
