Rapid Visual Survey of Existing Buildings in Gandhidham and Adipur Cities, Kachchh, Gujarat

Abstract

Bhuj earthquake of 26 January 2001 caused 14,000 casualties. Main reason for such huge casualties is low earthquake awareness and poor construction practices. Based on the technology advancement and knowledge gained after earthquake occurrences, the seismic code is usually revised. Last revision of IS 1893 (Criteria for earthquake resistant design of structures) was done in 2002 after a long gap of about 18 years. Some new clauses were included and some old provisions were updated. Assuming that concerned authorities will take enough steps for code compliance and the structures that are being constructed are earthquake resistant. In this light, what will happen to the safety of precode revision structures? These structures carry major percentage of vulnerable structure stock. Even if we have a very good disaster response system, it is impossible to reduce earthquake damage without considering the safety of precode revision structures. In this regard, a comprehensive study of seismic risk assessment of Gujarat is necessary. As a pilot study, government of Gujarat selected Gandhidham and Adipur cities in Kachchh district. Rapid Visual Screening (RVS) was conducted on 16000 buildings in Gandhidham and Adipur cities. Though, there are varied construction practices, about 26% of buildings were predominantly RCC type and 74% of masonry structure were found. RVS score of these structures reveal that in general buildings are of low quality and further evaluation and strengthening of buildings is recommended. The procedure adopted in this study is threetier method, i.e., Tier 1. Rapid Visual Screening, Tier 2. Preliminary assessment and Tier 3. Detailed assessment.