Study On Wind-induced Interference Effects Of Circular Section Chimney

Circular section chimney are widely used in electric power, thermal, petroleum,mining and other industries, it is a typical high-rise wind-sensitive structure with highheight, thin shell and light weight. Thus, wind load is always one of the maindomainting load in chimney design. Design codes provide some reference forcalculation of wind load on isolated chimneys. However, in practice, chimneys donotalways exist alone, and then the interference effects between chimneys cannot beignored. In some cases, the wind load in double chimneys is much greater than that ofan isolated chimney. Therefore, it is necessary to conduct a research on interferenceeffects.Based on the technique of simultaneous pressure measurement, the wind loadcharacteristics of single circular section chimney and the interference effects ofdouble chimneys are studied in this dissertation. The major contents of thedissertation can be summarized as follows.Firstly, wind pressure coefficient, stratified wind load ect. of single chimney areanalysed from the circular structure characteristic of wind load and its influencingfactors, and then point out the changes of drag coefficient with altitude and make acontrast with recommended value of load code.Secondly, the interference effects of static force are analysed base on the resultsof pressure measurements. Then, wind pressure coefficient, mean stratified wind load,base moment etc. of two different height and diameter chimneys are disscussed on thecondition of with or without interference chimney. Contrast the typical measuringpoints wind load characterists of new chimney and old chimney on different relativepositions with or without interference chimney, then point out the relations betweeninterference effects, scope and the relative positions and altitude.Lastly, double chimneys dynamic interference effects are analysed. Taking newchimney as example, along-wind equivalent static wind load and wind-inducedresponse are studied and found that the along-wind dynamic response is not promoted significantly. However, the cross-wind-induced vibration analysis reasults show thatold chimney has a great amplification effect on cross-wind dynamic response of newchimney, a dynamic magnification factor should be considered on structure design.