Title: Modal Characteristics of Linearly Tapered Reinforced Concrete Chimneys
Author(s): Wadi S. Rumman
Publication: Journal Proceedings
Appears on pages(s): 531-536
Keywords: bending moments;chimneys;dynamic loads; earthquakes; moments; reinforced concrete; shear properties; structural design; vibrations; wind pressure.
Modal characteristics are important in calculating the response of chimneys to wind and seismic forces. Although first mode characteristics are relatively easy to obtain, the characteristics of higher modes involve extensive computations. The purpose of this paper is to establish coefficients for the periods and mode shapes of reinforced concrete chimneys and other cantilevered structures with hollow circular cross section that vary linearly in both mean diameter and thickness. These coefficients are used to obtain approximate values for periods and mode shapes for actual chimneys. Once the periods and mode shapes are knpwn, the modal shears and moments are easily obtained. The first, second, and third modes are considered.