Aspects of across-wind loads and effects on large reinforced concrete chimneys

Research on the across-wind loads and effects on concrete chimneys has progressed to the point where reliable predictions for isolated, plain chimneys can now be made. This is not the case, however, for grouped chimneys and chimneys where the cross-section is not circular. In the former case, the wind loads are affected by the presence of one or more upstream chimneys. In the latter, wind tunnel studies can be used for sharp edged cross-sections, but when relatively slight modifications are made to the cross-section, the impact on the aerodynamics is not known. The present work is based on these two areas.; The work begins with a brief review of cylinder aerodynamics and a review of the work of Vickery and co-workers on the prediction of the across-wind response for chimneys.; The first part of the original work deals with how the response to across-wind loads is affected by foundation flexibility. In particular, for chimneys with freestanding liners, the interaction between the liner and concrete shell increases the relative deflections and introduces wind-induced stresses in the liner. A soil-structure interaction model is introduced that accounts for the flexibility of the foundation and predicts field observations.; A field and model study of wind loads on pairs of chimneys or cylinders is examined next. The field results are summarized. The model study, conducted at Re = 106 compared to Re = 107 full-scale, covers three diameter ratios and covers streamwise separation ratios between three and six diameters and transverse separation ratios of up to 1.5. The effect of the upstream cylinder on the across-wind loading for the downstream cylinder is examined.; The last part of the work deals with a slight modification from the circular cross-section and how this affects the aerodynamic loads and aeroelastic effects. Results for a wind tunnel study at Re = 5 × 105 are used to make post mortem predictions for a chimney that experienced an increase in the across-wind motions by a factor of ten.