A new methodology for analysis of equivalent static wind loads on super-large cooling towers

Abstract

For tall buildings and typical long-span spatial structures, the background and resonant components of wind-induced fluctuating response should be taken into account by different calculation theories. The total fluctuating response is obtained through the square root of sum of squares (hereafter referred to as SRSS) combination (hereafter referred to as tri-component method). However, this method cannot consider the modal coupling effects of the background and resonant components, nor the coupling effects of the resonant component for super-large cooling towers. This paper presents a new approach for analyzing wind-induced responses and corresponding equivalent static wind loads (hereafter referred to as ESWLs) by a consistent coupling method (hereafter referred to as CCM) based on structural random vibration theory. Firstly, the refined definition of the cross term between background and resonant component is explained based on a mode-acceleration method, and covariance matrices of coupled elastic restoring force and resonant elastic restoring force are proposed. Secondly, based on covariance matrix theory, CCM is proposed for calculating the background and resonant components and for compensating the cross term between background and resonant components, and the ESWLs of all components are derived by load response correlation theory. Finally, calculation of wind-induced responses and ESWLs for a super-large cooling tower 215m high demonstrates the superiority and effectiveness of the present approach, the characteristics of ESWL distributions of background, resonant and cross term between background and resonant component, and the wind-induced coefficients for super-large cooling towers are extracted.