Dynamic Response of Tall Chimneys on Pile–Raft Foundation Subjected to Wind Load

Abstract

Tall and slender structures like chimney and towers are used generally in the power plants and telecommunication industry, respectively. For such structures with extreme heights and dynamic performance, the effect of wind load will have an important role in the design. The present paper evaluates the effect of deterministic wind load on the dynamic response of chimney. For depicting the restraint conditions of the structure in a realistic manner, soil flexibility (soil–structure interaction effect) has been considered while performing the analysis. For the wind analysis, along-wind effect has been considered. This paper explores the chimney considering nonlinear Soil–Structure Interaction (SSI) effects using Beam-On-Nonlinear-Winkler-Foundation (BNWF) approach. A 220-m-high RCC chimney of truncated hollow cone shape has been taken from the case study. The chimney is supported by a pile–raft foundation consisting of 332 bored cast in situ piles on a clayey silt deposit. The chimney has been assumed to be located in open terrain and subjected to a maximum wind speed of 50 m/s. The along-wind loads were computed according to IS: 875(Part 3) and applied along with the height of the chimney. Two-dimensional finite element (FEM) analysis is performed using OpenSees based on the direct method of SSI. Theoretical evaluation of the response considering beam elements for the chimney, pile, pile cap, and spring elements for SSI has also been a part of the study. Displacement responses of the chimney have been considered with both fixed base and flexible base conditions. The study demonstrates the influence and need for consideration of SSI which will properly estimate the response of a structure.