Damage, deterioration and the long-term structural performance of cooling-tower shells: A survey of developments over the past 50 years

The last 50 years have seen a gradual shift in trend in research on concrete hyperbolic cooling-tower shells, from the issues of response to short-term loading and immediate causes of collapse in the early part of this period, to the issues of deterioration phenomena, durability and long-term performance in more recent times. This paper traces these developments. After a revisit of some historical collapses of cooling-tower shells, and a brief consideration of condition surveys and repair programmes instituted in the aftermath of these events, focus shifts to the important question of damage and deterioration, and progress made over the past 30 years in the understanding of these phenomena. In particular, much research has gone into the modelling of cracking and geometric imperfections, which have a considerable effect on the load-carrying capacity of the shell, and are also manifestations of long-term deterioration. While structural monitoring of the progression of deterioration in cooling-tower shells, and the accurate prediction of this through appropriate numerical models, will always be important, the thinking now seems to be shifting towards designing for durability right from the outset.