lecture#17
DESCRIPTION
Lecture#17. CE-312 Engineering Geology and Seismology Instructor: Dr Amjad Naseer. Department of Civil Engineering N-W.F.P University of Engineering and Technology, Peshawar. Outlines of the Presentation. Seismic Risk Seismic Hazard Assessment - PowerPoint PPT PresentationTRANSCRIPT
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CE-312
Engineering Geology and Seismology
Instructor:
Dr Amjad Naseer
Lecture#17
Department of Civil Engineering
N-W.F.P University of Engineering and Technology, Peshawar
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• Seismic Risk
• Seismic Hazard Assessment• Deterministic Seismic Hazard Assessment (DSHA)
• Probablistic Seismic Hazard Assessment (PSHA)
Outlines of the PresentationOutlines of the Presentation
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Seismic RiskSeismic RiskSEISMIC RISK refers to the amount of damage to be expected with a certain probability in a fixed period time. It is the composition of
RISK =HAZARD * EXPOSURE * VULNERABILITY
The hazard is controlled by Nature.
Vulnerability and Exposure are controlled by humans.
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Seismic RiskSeismic Risk
• Seismic hazard is the probability of observing a certain ground shaking (e.g., PGA, macro-seismic intensity, etc.) in a fixed time period.
• Vulnerability is the tendency of a structure to suffer damage.• Exposed value is an economic, but also social, quantification
of the object exposed to earthquakes.
Nature Engineers Planners
7Seismic Hazard Zoning Map
“Natural” Disasters and Casualties
Economic Impact of Earthquakes
The Gross National Product (GNP) is the total dollar value of all final goods and services produced for consumption in society during a particular time period.
HAZARD * EXPOSURE * VULNERABILITY * COST
Assess
ReduceBalance
Seismic Risk Mitigation
Control
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• The different sources of seismicity around a site are
identified and an earthquake scenario is fixed for each of
source. The location of the scenario is usually taken to be at
the least favourable location, in other words at the closest
approach to the site, possibly such that the site will also
experience forward directivity effects. The magnitude of
each scenario is a more difficult subject to select.
• However, the results of a deterministic analysis are far
more sensitive to the choice of upper-bound magnitude
than a probabilistic analysis. The term generally used to
define the size of the controlling event is the Maximum
Credible Earthquake (MCE), although there are many who
argue for this term to be abandoned.
Deterministic Seismic Hazard Assessment (DSHA)Deterministic Seismic Hazard Assessment (DSHA)
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• Once the design scenarios are fixed in terms of magnitude
and distance from the site, it is a very straightforward
operation to estimate the resulting levels of ground motion
using attenuation relationships. The most onerous ground
motion can then be taken as the basis for design, although
in some cases it may be necessary to consider more than
one scenario if the ground motions do not show a single
clearly dominant case.
Deterministic Seismic Hazard Assessment (DSHA)Deterministic Seismic Hazard Assessment (DSHA)
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Deterministic Seismic Hazard Assessment (DSHA)Deterministic Seismic Hazard Assessment (DSHA)
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• Once the design scenarios are fixed in terms of magnitude
and distance from the site, it is a very straightforward
operation to estimate the resulting levels of ground motion
using attenuation relationships. The most onerous ground
motion can then be taken as the basis for design, although
in some cases it may be necessary to consider more than
one scenario if the ground motions do not show a single
clearly dominant case.
Deterministic Seismic Hazard Assessment (DSHA)Deterministic Seismic Hazard Assessment (DSHA)