Probabilistic Seismic Hazard Assessment: The Basics to State-of-the - - PowerPoint PPT Presentation

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Probabilistic Seismic Hazard Assessment: The Basics to State-of-the - - PowerPoint PPT Presentation

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Probabilistic Seismic Hazard Assessment: The Basics to State-of-the Art Research NOVA Science Seminar Dr. Annie Kammerer, P.E. February 2010 1 Overview Earthquake basics Earthquake effects Calculating hazard Research topics

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Probabilistic Seismic Hazard Assessment:

The Basics to State-of-the Art Research

NOVA Science Seminar

  • Dr. Annie Kammerer, P.E.

February 2010

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Overview

  • Earthquake basics
  • Earthquake effects
  • Calculating hazard
  • Research topics
  • Structural response

(if there’s time)

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Plate Tectonics

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US National Hazard Mapping

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Interplate Regions

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Intraplate Regions

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Types of Hazards

  • Surface rupture
  • Strong shaking
  • Fire
  • Landslides
  • Liquefaction
  • Tsunami
  • Dam/Levee failure
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Types of Hazards

  • Surface rupture
  • Strong shaking
  • Fire
  • Landslide
  • Liquefaction
  • Tsunami
  • Dam/Levee failure

Primary Effects Secondary Effects

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Types of Hazards

  • Surface rupture
  • Strong shaking
  • Fire
  • Landslide
  • Liquefaction
  • Tsunami
  • Dam/Levee failure
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Surface Rupture

Santa Cruz Mountains (1989)

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Landslide

Santa Cruz Mountains (1989)

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Fire

– Broken gas mains – Broken lines to water heaters – Overturned stoves – Lack of water – Big cause of damage (SF, Kobe)

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Fire

Northridge (1994)

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Liquefaction

Liquefaction occurs when saturated loose sands and hydraulic fills experience strong shaking. The soil degenerates into a thick soupy material.

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Liquefaction

  • Foundation

failures

  • Breakage of

pipes

  • Floating of

underground tanks

  • Sand boils
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Liquefaction

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Liquefaction

Niigata earthquake 1964

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VIDEOS

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N1,60,CS

10 20 30 40 CSR* 0.0 0.1 0.2 0.3 0.4 0.5 0.6

MW=7.5 σV'=1.0 atm

PL

80% 20% 95% 50% 5%

Liquefied Marginal Non- liquefied Pre-1985 Data “New” Data

Capacity Demand How do we know if there’s a problem?

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N1,60,CS

10 20 30 40 CSR* 0.0 0.1 0.2 0.3 0.4 0.5 0.6

MW=7.5 σV'=1.0 atm

PL

80% 20% 95% 50% 5%

Liquefied Marginal Non- liquefied Pre-1985 Data “New” Data

Strength of the soil as measured by poking holes in the ground with special equipment How hard the earthquake will shake the site

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Performance-Based Design

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How hard will the rock shake?

Strong Shaking

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How does the rock shake? How does the soil react?

Strong Shaking

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How does the rock shake? How do the building and contents react?

Strong Shaking

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  • Magnitude
  • Distance from fault to site
  • Geology of path and site
  • Structure

Strong Shaking

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How do we know how hard the rock shakes?

  • Deterministic seismic hazard

assessments (DSHA)

  • Probabilistic seismic hazard

assessments (PSHA)

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Deterministic assessments

  • Worst case based on known faults
  • Need fault information and ground motion

prediction equations (attenuation relationships)

  • Problems determining what the worst case is
  • Different risk levels for different sites
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Ground Motion Prediction Equations

0.01 0.10 1.00 10 20 30 40 50 60 70 80 90 100

Distance (km)

Abra.-Silva (1997) Rock USGS 2002 Boore-Joyner-Fumal (1997) USGS 2002 Source Type: All Faults Magnitude: 7 Mw Period: 2 seconds Shear Wave Velocity: 760 meter/sec Basement Rock Depth: 3 km Alluvium Thickness: 1 m Focal Depth: 6 km

Magnitude 7

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Ground Motion Prediction Equations

0.01 0.10 1.00 10 20 30 40 50 60 70 80 90 100

Distance (km)

Abra.-Silva (1997) Rock USGS 2002 Boore-Joyner-Fumal (1997) USGS 2002 Source Type: All Faults Magnitude: 7 Mw Period: 2 seconds Shear Wave Velocity: 760 meter/sec Basement Rock Depth: 3 km Alluvium Thickness: 1 m Focal Depth: 6 km

Magnitude 7

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Probabilistic assessments (PSHA)

  • The way the NRC does it (RG 1.208)
  • Considers the probability of different

events over time

  • 10,000 year earthquake (sort of like the

100 year flood)

  • More complex analysis
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PSHA

Find effects of all possible earthquakes, multiply each by the likelihood it will actually happen, combine the events

For each spectral frequency

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PSHA

For each spectral frequency

1 2 0.1 1 10 100 Frequency (Hz) Spectral Acceleration (g)

Mean Rock UHRS 1 E-6/yr

Uniform Hazard Response Spectrum (UHRS)

Acceleration (g) Natural Frequency

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Natural frequency

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1 2 0.1 1 10 100 Frequency (Hz) Spectral Acceleration (g)

Mean Rock UHRS 1 E-6/yr

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PSHA

1 2 0.1 1 10 100 Frequency (Hz) Spectral Acceleration (g)

Mean Rock UHRS 1 E-6/yr

Uniform Hazard Response Spectrum (UHRS)

Acceleration (g) Natural Frequency

How hard the rock shakes

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Soil Amplification

Soil Rock

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Site Response Computer Model

0.1 1 10 0.1 1 10 100 Frequency (Hz) Response Spectral Ratio

Low-Frequency Site Amplification Function High-Frequency Site Amplification Function

Divide shaking at top by the input motions

Amplification Frequency

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Soil-based uniform hazard response spectrum

1 2 3 0.1 1 10 100 Frequency (Hz) Spectral Acceleration (g)

1 E-5 Mean Soil UHRS Mean Rock UHRS Scaled By Low-Frequency Amplification Function Mean Rock UHRS Scaled By High-Frequency Amplification Function

0.1 1 10 0.1 1 10 100 Frequency (Hz) Response Spectral Ratio

Low-Frequency Site Amplification Function High-Frequency Site Amplification Function

1 2 0.1 1 10 100 Frequency (Hz) Spectral Acceleration (g)

Mean Rock UHRS 1 E-6/yr

X

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Ground Motion Response Spectrum (GMRS)

Multiply UHRS by design factors to account for risk to get GMRS GMRS is used to determine the safe shutdown earthquake (SSE) ground motion

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US NRC Projects to Assess Seismic Hazard in CEUS Source Characterization Ground motion prediction equations Framework for large PSHA studies

Central and Eastern US Seismic

Source Characterization project for Nuclear Facilities (CEUS SSC) Next Generation Attenuation Relationships for the Central and Eastern (NGA-East) Recommendations for Implementation

  • f SSHAC Guidelines for Level 3

and 4 Processes

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Structural dynamics

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Structural dynamics

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Structural dynamics

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Group Participation

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Soil Structure Interaction (SSI)

Picture from Gazetas et al.

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Questions?