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17WCEE

The following papers were presented at the 17th World Conference on Earthquake Engineering (17WCEE) at Sendai International Center, Sendai, Japan from 27 September to 2 October.

Seismic performance of RC tall building with columns resting on transfer storey – Pulkit D Velani and Prof. R Pradeep Kumar. Research work as explained by the authors: 

Constructions of tall buildings with discontinuous vertical elements, such as columns and structural walls are quite common in India. Such structural form exists to cater the functional need of obstruction free large area for the purpose of vehicular parking or use it for common amenities. Many a time such structural forms are adopted to satisfy the aesthetic requirement desired by owner or architect. In order to accommodate this vertical discontinuity, vertical elements are typically supported on a transfer girder. This transfer girder has to transfer the vertical and lateral load from upper storey to storey below it. However, such feature creates abrupt change in storey stiffness leading to localised damage near transfer storey, during a major earthquake. Current comparative study is an attempt to understand the increased demand in storey drift for a reinforced concrete moment resisting-structural wall building, with and without a transfer slab. For this purpose three dimensional finite element models of two towers have been created. And the effect of transfer storey on global seismic performance of both the tower, under linear time history analysis, was observed by comparing their inter storey drift, and storey displacements. Finally, the building with a transfer slab found to be inappropriate for seismically active regions.

  • Earthquake Disaster Risk Index – A Simple Method for Assessing Relative Risk in a Country – Prof. R Pradeep Kumar , Prof. C V R Murty, IIT Madras. Research work as explained by the authors: 

The UN World Conference on Disaster Risk Reduction held in 2015 at Sendai, Japan, reiterated the need for substantial reduction in loss of life and property. Thus, assessing disaster risk and identifying key items for risk mitigation are in focus. Assessment of disaster risk is a multidisciplinary effort, which includes expected tangible physical loss, such as collapse and damage to the built environment. In countries with limited resources, prioritizing risk reduction effort across the different parts of the country needs a quantitative (yet simple) approach to bring objectivity into the decision-making process.

This paper presents a simple method, called Earthquake Disaster Risk Index (EDRI), for estimating relative earthquake risk across the different regions in a country; it uses three major constituents of risk, namely Hazard, Exposure and Vulnerability. Hazard is taken as the acceleration hazard specified in the national earthquake design standard, Exposure as per the permitted occupancy in the Local Municipal Byelaws, and Vulnerability through a Level 2 Detailed Qualitative Assessment of buildings built in the Town or City (with penalty points for missing features of earthquake resistance compared to an Ideal Building). First, the EDRI of a Town or City is estimated for each typology of building in the Town or City, and then the net EDRI of the Town or City is obtained as a weighted average of the EDRI of each typology of buildings using the number of buildings of each typology present in the city.

The EDRI of a city so estimated can be compared with that of another city. Also, disaggregation of risk through its three major constituents of EDRI will increase awareness of the factors which contribute to risk – from expected intensity of earthquake ground shaking, to exposure of people in each building type, to vulnerability of each building typology. The exercise can be undertaken at a large scale across the country. Policy Makers of a prefecture or a state in a nation will find the results of EDRI to be a useful tool for prioritising allocation of earthquake risk mitigation resources and effort across Towns and Cities.