International Research Journal of Engineering and Technology (IRJET) Volume: 09 Issue: 06 | Jun 2022
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e-ISSN: 2395-0056 p-ISSN: 2395-0072
PROBABILISTIC SEISMIC HAZARD ANALYSIS FOR SEISMIC RISK ASSESSMENT Miss. Aastha 1, Dr. R. R. Singh2 Ph.D. Student, Civil Engineering Department Punjab Engineering College (Deemed To Be University) Chandigarh India Postal code: 160012 2 Professor, Department of Civil Engineering Punjab Engineering College (Deemed To Be University), Chandigarh, India Postal code: 160012 ---------------------------------------------------------------------***--------------------------------------------------------------------1
Abstract - Earthquakes have been a significant area of
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concern since its occurrence has been associated with huge loss of lives and the region's economy. This concern has led various groups of scientists from different fields to work in tandem with governments to quantify this and further mitigate the losses accompanying these events. Thus, Seismic Risk Assessment came into existence ic Risk refers to the possibility of damage to a locality in terms of injuries, fatalities, material, and monetary loss. A famous saying, "Earthquakes don't kill people, buildings do. Seismic Risk consists of components such as Seismic Hazard, Vulnerability of Building, and Exposure Seismic Hazard deals with the Intensity measures produced due to Earthquake These Intensity measures are further used in Vulnerability to compute the damage caused by these to the structures. Lastly, exposure deals with estimating the population affected by the damage caused to these structures. Thus, the loss in fatalities, injuries, economic loss due to structural damage, etc., can be estimated. Seismic Hazard deals with the prediction of Intensity Measures (like PGA, PGV) occurring at a site, assuming an earthquake of a given Magnitude occurs at a selected fault source. Seismic Hazard is an integral part of Risk Assessment. It acts as an input parameter for computing Vulnerability. Seismic Hazard computation is further done based on Deterministic and Probabilistic Methods. These methods follow a similar approach for hazard calculation. But as these have developed over different periods, thus these are based on different assumptions. So, the objective of this paper is to understand the working of the PSHA module in Risk IITB
1.1 DSHA Deterministic Seismic Hazard Analysis (DSHA) is the simplest method of Hazard Assessment based on the tectonic and geological features of the area and its historical seismicity. DSHA involves considering Maximum Credible Earthquake (MCE), either assumed or realistic, centered on a fault, source-to-site distance, and Magnitude considered. It is one of the most widely used methods to calculate the Risk of a critical structure for design purposes. DSHA is described as a four-step process: 1. Identification and characterization of the earthquake sources. It includes defining each source's geometry and earthquake potential based on the available knowledge. 2. Ascertain the distance from the site to source This distance is generally the shortest distance from source to site, called Joyner-Boore distance. Still, it differs based on the attenuation relationship considered for Analysis in some cases. 3. Selection of the Magnitude of the Seismic Activity. In general, two magnitudes are defined, one for design purposes and the other for safety purposes. The magnitudes are either chosen based on historical activity at the site or they can be estimated using fault scaling relations based on fault dimensions.
Key Words: Probabilistic Seismic Hazard Analysis (PSHA), Deterministic Seismic Hazard Analysis (DSHA)
4. Predicting the ground motions produced. The ground motion values predicted are based on the th variability considered Generally ε=1 or 84 percentile values are considered as maximum ground motion values affecting the site
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1.2 PSHA Probabilistic Seismic Hazard Analysis in practice for the last 20-30 years due to its comprehensive way of analyzing the Risk associated with ground motion at the a particular
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