The Design of Two Unusual Structures at York University

This paper describes the design and construction of a tall chimney and a water-tower for the University of York. Both structures are of reinforced concrete and involve unusual proportions and shapes which are potentially susceptible to wind-induced vibrations. During the design stage their behaviour was fully investigated by testing models in a wind tunnel. Observations were made both of the static wind pressures on the models and of the unsteady wind effects upon them. For the latter observations models were constructed to reproduce to the appropriate scales the dynamic properties of the structures. The range of the experiments included the influence of the liquid contents of the water-tower and the effect of the high structural damping inherent in reinforced concrete. Measurements of the structural damping that were made on the completed chimney structure gave values of the logarithmic decrement in the range 0 075 to 0.115. It was concluded that the high structural damping was an important factor in ensuring the stability of the chimney.

G.M.J. Williams, Professor D.S. Houghton and G.M. Moss