Calls for retrofitting, other measures to lessen damage
Irfan Tramboo
Srinagar, Apr 12: A recently conducted study has found that the residential buildings constructed in the northern part of Jammu city which lies on the right bank of the Tawi river, are extremely vulnerable to earthquakes.
Prof. Abdullah Ansari, Prof. K. Seshagiri Rao, Prof. Arvind K. Jain from the Department of Civil Engineering at the Indian Institute of Technology in Delhi, Falak Zahoor from the National Institute of Technology in Srinagar, and Tanzeel Ur Riyaz from the Deptt. of Civil Engineering at the RIMT University in Punjab are the authors of the study titled ‘Seismic Vulnerability of Residential Buildings in Jammu City, Jammu and Kashmir’ which has been published in Springer’s Soil Dynamics, Earthquake and Computational Geotechnical Engineering, Lecture Notes in Civil Engineering-Volume 300.
It attempted to assess the seismic vulnerability of residential buildings in Jammu city by conducting an intensive field survey and collecting data from 75 wards related to demographic framework and structural specifications, while separate seismic vulnerability maps were prepared based on building density, population ratio, building height, building age, and construction material.
“All these five factors together play a significant role in deciding the seismic vulnerability of any structural element. To study the combined effect of all these five parameters, the logic tree framework was adopted with an equal weightage of 0.5 for both demographic framework and structural specifications. One-third part of Jammu city falls under the high to very high vulnerability class. The northern part of the city which lies on the right bank of the Tawi River is more vulnerable compared to the southern part,” it states.
During the survey, the data for 225 buildings were collected from 75 wards in Jammu which were used to evaluate the seismic vulnerability of residential buildings located in Jammu city.
“According to building density, 15 wards covering 20% of the total area fall under the ‘Very Low Vulnerability’ category; 19 wards covering 25.33% under the ‘Low Vulnerability’ category; 12 wards cover 16% of the total area fall under ‘Medium Vulnerability’ category; 17 wards covering 22.67% of area fall under ‘High Vulnerability’ category, and 12 wards covering 16% of the total area fall under ‘Very High Vulnerability’ category.”
It stated that about 8%, 54.67%, and 37.33% of wards fall under the group, low vulnerability, medium vulnerability, and high vulnerability, respectively, as per population ratio. While based on building age, 29 wards covering 38.67% of the total area fall under the ‘Very Low Vulnerability’ category; 3 wards covering 4% of the total area fall under the ‘Low Vulnerability’ category; 5 wards covering 6.67% of the total area fall under ‘Medium Vulnerability’ category; 8 wards covering 10.67% of the total area fall under ‘High Vulnerability’ category, and 30 wards covering 40% of the total area fall under ‘Very High Vulnerability’ category.
“About 25.33, 34.67, and 40% of wards fall under the class, low vulnerability, medium vulnerability, and high vulnerability, respectively, as per building height. According to the quality of construction material, out of 75, 11 wards fall under low vulnerability, 40 wards under medium vulnerability, and 24 wards under the high vulnerability category.”
In terms of building density, the study found that the majority of Jammu City falls under the “Medium Vulnerability” category, while the population ratio for the city’s outside districts is lower, causing it to fall under the “Low Vulnerability” category.
“To assess the seismic vulnerability based on structural specifications, three important factors, building height, building age, and material for construction are taken under consideration.”
Due to urbanization, the study said, the construction of new buildings with multi-storey has become a trend and in Jammu, most of the buildings have 3+ storeys which lead the maximum part of the city to fall under the ‘High Vulnerability’ zone.
According to the study, it is crucial to modify residential structures in seismically active areas to prevent structural damage and guarantee occupant safety. “An immediate action needs to be made to prevent any catastrophic structural damage brought on by any future far-field or near-field earthquake…The vulnerability of these residential structures can be decreased through the retrofitting process,” the study noted, adding that the findings can be applied to the construction of new residential structures in seismically active areas like Jammu and Kashmir.
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