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1) Earthquake Early Warning System (EEWS)
1) Earthquake Early Warning System (EEWS)
Starting from 19th May, 2020, I have been working on EEWS. This project is a collaboration of Duke University and Pulchowk Campus. There are three teams: Team Attenuation, Team Hazard, and Team Electronics & Sensors. At present, I'm building a hazard and risk map for Nepal under Team Hazard.
Probabilistic Seismic Hazard Analysis
We started off with determining locations to fix the earthquake sensors in Kathmandu Valley based on a liquefaction map. Moving on, after studying the advanced procedure of Seismic Hazard Analysis, we declustered the earthquake catalog using Matlab & Openquake software. The Duke Team is preparing earthquake source zones using K-mean clustering. We Nepal Team are reiterating a precise ground motion prediction equation that can accurately capture the long period spectrum. Our next step is to prepare the hazard map for the country.
Retrofitting Cost-Benefit Analysis (BCR)
There are many researches that have been conducted in past under earthquake risk analysis for Nepal. However, after Gorkha 2015 Earthquake, retrofitting cost benefit analysis is on high demand. we are trying to impose retrofitting measures and then analyze the economical benefits after imposing the improvement techniques. Initially, we provide specific input to OpenQuake model as shown in above flowchart. OpenQuake later provides the Benefit Cost Ratio Maps (BCR). Right now, we are trying to develop vulnerability curves for the buildings of Nepal using OpenSees and Vulnerability toolkit.
2) Poster Presentation (Symposium 2020)
2) Poster Presentation (Symposium 2020)
On January 3, 2020, my team presented the results of our six month progress in student research symposium. This was held in IHUB, Nepal under the collaboration of US embassy. I presented one of the posters on the topic "Uncertainty propagation through PSHA due to Gutenberg 'b' value."
3) Suitability of Stone Columns in Kathmandu Valley
3) Suitability of Stone Columns in Kathmandu Valley
In 2020, my team started working on feasibility analysis of stone columns in Kathmandu Valley. For this, we collected SPT 'N' values to assess the soil properties. We evaluated the bearing capacity of soil under mat and isolated footing. Thereafter, analyzed the settlement properties of soil. Finally, we compared the soil characteristics before and after inclusion of stone columns using Plaxis 3D software.
Stone column, one of the most economical and widely used methods, enhances the soil properties by increasing bearing capacity, reducing settlement, and improving the liquefaction reduction potential, especially in soft clays. Kathmandu Valley consists of a dynamic subsoil profile; due to haphazard urbanization within the valley, utilizing an effective method to mitigate any forthcoming geotechnical problems is of utmost importance. The study showed that bearing capacity increases on increasing stone column depth, diameter; and reduces on increasing the spacing between them in clayey soil. The settlement reduction factor and liquefaction reduction potential also increased on strengthening the soil with the stone column. There is a high feasibility of improving soil properties on installing the stone column in Kathmandu Valley; nevertheless, further detailed studies are required to determine the optimum stone column dimension in case of weak layers and also to impart better confinement and stiffness according to the subsoil profile.
4) Assessment of Changes in Building Eccentricity and Torsional Irregularity
4) Assessment of Changes in Building Eccentricity and Torsional Irregularity
This study is a step toward an easier and simpler approach to minimize the translational-torsional coupling effect in eccentric buildings with smaller column sizes. The results are highly significant because incorporating eccentric buildings with shear walls or bracing systems cannot always be a viable alternative due to aesthetic and economic constraints. A much simpler solution to reduce the eccentricity is presented using an approach called the “Conventional Evaluation Method”. The torsional irregularity, eccentricity, and reinforcement demand were reduced after resizing less stiff columns of buildings.
An elaborative technique for correction of structural response in building with torsional irregularity is presented which is assessed by changing the lateral stiffness of vertical structural members. Moreover, a simplified approach to evaluate the stiffness of structural member and center of rigidity has been presented i.e. Conventional Evaluation Method. The described method (Conventional Evaluation Method) is used to study and differentiate the eccentricity and rigidity obtained from Finite Element Analysis. Effective resizing of particular columns helped to achieve a reduction in horizontal displacement subsequently, minimizing eccentricity and torsional irregularity.
5) Integrated Seismic Risk Assessment of Nepal
5) Integrated Seismic Risk Assessment of Nepal
With my team, we have developed integrated risk approach for the first time in Nepal to present combined spatial variability of earthquake risk and social vulnerability for the entire country Nepal.
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