Faculty Publications
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Item Deterministic seismic hazard analysis of Ahmedabad Region, Gujarat(2012) Rao, K.S.; Thaker, T.P.; Aggarwal, A.; Bhandari, T.; Kabra, S.Deterministic seismic hazard analysis of Ahmedabad region has been carried out considering past earthquake data and available seismotectonic information. Earthquake catalogue of the region covering 350 km radius around the Ahmedabad city has been generated separately after processing of collected earthquake data since 1668 to 2010. Declustering of entire catalogue has been carried out to remove the dependent events. Shortest distances from each seismic source causing tectonic activity have been calcuPGA) values at rock level have been estimated using predictive relationships for the region. Our analysis shows that peak ground acceleration from Ahmedabad region has been varied from 0.14 to 0.44 g with maximum credible earthquake (MCE) of magnitude 6.1 generated from East Cambay Fault. The PGA model presented in this article provides basic design parameters for the Ahmedabad region. © 2012 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Synthesis of Linear JTFA-Based Response Spectra for Structural Response and Seismic Reduction Measures for North-East India(World Scientific, 2020) Devaraj, D.; Ramkrishnan, R.; Prabu, T.; Kolathayar, S.; Sitharam, T.G.North-East India (NEI) has a long history of devastating earthquakes due to the complicated tectonic setting of the region. A shortage of sufficient recorded time-histories from the region calls for a synthesis of accelerograms for dynamic analyses. In this study, a novel Joint Time-Frequency Analysis (JTFA) technique is adopted for the synthesis of accelerograms, considering the non-stationary behavior of earthquake waves. JTFA is used for analyzing the signals in a joint time and frequency domain to better understand its characteristics and synthesize signals without compromising its inherent characteristics like frequency content and amplitude. Synthetic accelerograms are developed using JTFA techniques for different magnitude and distance ranges between 5 to 6.8 and 0-480km and response spectra are developed. Synthesized generalized accelerograms and their response spectra are compared with actual signals in the same magnitude-distance ranges and were found to match. A comparison of the frequency contents of actual and synthetic signals was also carried out using Fourier Transforms and spectrograms (SPs) and was found to be in good agreement. Further, a comparative study of various earthquake reduction measures for NEI is carried out for a scenario earthquake using the synthesized data, and the best suitable structural input for the region is recommended. © 2020 World Scientific Publishing Company.Item Ground motion duration predictive models applicable for the Himalayan region(Springer, 2023) Anbazhagan, P.; Motwani, K.Several empirical models for the prediction of ground motion duration were developed across the world, but no model has been generated for the Himalayan region in the past. In this study, an attempt is made to study the duration models developed for different regions and compare them with a reference model developed for the Himalayan region for a wide range of magnitudes. The comparison is performed using the log-likelihood method and aims to identify the best duration prediction models based on the developed by Bajaj and Anbazhagan (2019) for the study region. The data support index values along with the weights of the corresponding models across the different distances and magnitude ranges have also been estimated. The study found that the predictive duration relation given by Lee and Green (2014) for Western North America is suitable for M ≤ 5, while the model developed by Ghanat (2011) is suitable for M > 5 for the Himalayan region. The model developed by Afshari and Stewart (2016) is also very close to the reference model. It is always preferable to have a single duration predictive model for a wide range of magnitude and distance range; hence, there is a need to develop a region-specific duration predictive model for the Himalayan region. © 2023, Indian Academy of Sciences.Item Novel technique to mitigate the earthquake-induced damage of rubble mound breakwater(Elsevier Ltd, 2024) Akarsh, P.K.; Chaudhary, B.; Sajan, M.; Sah, B.; Kumar, S.In past, the 2004 Indian Ocean earthquake and the 2011 Great East Japan earthquake had caused collapse of many breakwaters due to failure of their foundations. The seismic behaviour of rubble mound (RM) breakwater is not well understood may be due to limited number of research works done in the area. Therefore, in the present study, a series of shaking table tests were conducted for RM breakwater in order to determine the exact reasons and mechanisms of failure of the breakwater during an earthquake. In addition, a novel countermeasure technique was developed to mitigate the earthquake-induced damage of RM breakwater. The countermeasure model dealt with geobags as armour units on the both sides instead of conventional armours to increase the stability. The developed model has geogrid and sheet piles in seabed foundation soils of the breakwater. The effectiveness of countermeasure model was examined by comparing with conventional RM breakwater model considering parameters like settlement, horizontal displacement, acceleration-time histories, excess pore water pressure and deformation patterns. Numerical analyses were done to elucidate the failure mechanisms. Overall, the developed model was found to be resilient breakwater against the earthquakes; and the technique could be adopted in practical use on the real ground. © 2023 Elsevier LtdItem Deterministic Seismic Hazard Analysis of Sree Padmanabhaswamy Temple, Kerala State(Springer, 2025) Padmanabhan, M.P.H.; Siddhardha, R.; Kolathayar, S.; Hegde, R.; Beekanahalli Mokshanatha, B.M.Deterministic seismic hazard analysis (DSHA) is a technique employed to estimate potential hazards and ground shaking resulting from specific earthquake scenarios at a given location. In the present study, DSHA is conducted for the Sree Padmanabhaswamy Temple, situated in the southernmost district of Kerala, India. This seismic hazard study is crucial due to the temple’s proximity to seismic events such as the 1900 AD Coimbatore earthquake with a magnitude of 6.3 Mw and the 2000 Pala earthquake with a magnitude of 4.7 Mw. This study examines earthquake data within a 500 km radius surrounding the Sree Padmanabhaswamy Temple in Thiruvananthapuram District, Kerala, from 1819 to 2022 AD. The seismic zone of the temple site is III according to the Indian zonation map (IS 1893 (Part 1): 2016), relying on past earthquakes recorded throughout India. The collected earthquake data underwent a homogenization process to determine the moment magnitude (Mw), distinguishing foreshocks and aftershocks from the main shocks. A seismotectonic map was developed comprising of geological discontinuities and 316 earthquakes events with moment magnitudes between 3.0 and 6.3 Mw. The software tools employed for this work include MATLAB, QGIS and ZMAP. The Log-likelihood technique (LLH) was used to choose the ground motion prediction equations (GMPEs) for the location. The GMPEs were then given weights based on the computed values of the data support index (DSI). The study region was partitioned into a grid size of 0.05° × 0.05° (5 km × 5 km). Using MATLAB code, the peak ground acceleration (PGA) was estimated for the site and PGA was found in the center of each grid cell, taking into account all seismic sources within a 500 km radius. In addition, site-specific deterministic spectrum was also developed. The findings show that Sree Padmanabhaswamy Temple has low seismicity, which is defined by weak to moderate earthquakes that have sources close to the temple. © The Author(s), under exclusive licence to Indian Geotechnical Society 2024.