Evaluation of Regional Demand Parameters for Design of Mid-high-rise Building Using Past Earthquake Records

Abstract

Category of earthquake and distance from epicenter are the prime parameters that decide the demand on buildings for its engineering. As observed in past Bhuj earthquake of 2001 (7Mw), seventy buildings got severely damaged in Ahmedabad city which is located 250kms from the epicenter. Intensity index through observed damages fills the gap for the demand anticipations. Design of a building considering excitation frequency rather than just the zone factor is necessary to include effects of low frequency waves (e.g. Mexico-city). This paper shows the broad ways in which seismic demand can be obtained for performing PBD in Indian context. A mid-rise RC building is designed as per three standard code of practices (i.e. IS, ACI, EN) to provide seismic resistance. The anticipated demand levels are obtained using GMPEs (PEER), magnitude-intensity relations, micro-zonation study and NDMA hazard contours for 15 storey building in Ahmedabad. The highest capacity curve is for design using IS 1893 code and this building will survive earthquake having 0.22g PGA value. The magnitude-intensity-epicentral distance relation (Gutenberg et al, 1956) shows that the intensity of VII for Zone-III is not correct for Ahmedabad city and it shall be taken as VIII which is for Zone-IV (0.24g) as per zoning map of India. However, as per the micro-zonation study showing PGA of 0.18g for the city it can be said that building will survive the next earthquake of 7.0Mw in Bhuj. The damage to non-structural elements is evident from the NLTHA using matched response spectrum obtained using Uttarkashi and Chamoli earthquake records (COSMOS). It is suggested to use intensity-based response spectrum for design of mid-high-rise buildings in Ahmedabad city. Moreover, a local directive based on social and technology resilience shall be developed to provide design basis based on loss (%)-multiple hazard (PGA) matrix using the matching relations found in this paper. Design provisions and loss reduction strategy can only lead to sustainable infrastructure in cities planning for vertical development.