Extreme wind climate modeling of some locations in India for the specification of the design wind speed of structures

Abstract

The wind load on a structure is proportional to the square of the wind speed. Extreme wind climate modeling should be required for specifying the design wind speed of structures. Extreme wind speeds for a storm type should be fitted in a suitable probability distribution, from which the design wind speed can be specified for a particular service life of a structure. The methodology, used in India for the specification of the design wind speed of existing structures, is fairly old and should be updated. Extreme wind climate in India is mainly influenced by thunderstorms and cyclones. Because thunderstorms and cyclones occur due to different geophysical reasons, it is necessary to fit extreme events of these two storm types in separate probability distributions, which can be subsequently combined to determine the overall non-exceedance probability. For a thunderstorm analysis, the wind speed data for three stations were considered, namely Kolkata, Lucknow and New Delhi. However, the statistical analysis greatly suffered due to the low ensemble size in Lucknow. Moreover, cyclones very rarely occur; as a result, cyclone modeling for the Bay of Bengal (total east coast) was initially considered to obtain a sufficient ensemble size. This paper provides a strategy to determine the specification of the design wind speed of structures at a particular location, which is affected by both thunderstorms and cyclones. The motivation of this work is to improve the current design methodology as well as the national code of standards to make engineering structures in India less vulnerable to damage due to strong winds.