Technique for precise measurement of large-scale silos and tanks

Geometric imperfections in thin-shell structures such as silos and tanks need to be measured to assess the buckling strength of the structures, and to develop new structure design criteria. A number of difficulties are associated with the task of imperfection measurements in such structures. This paper describes a new technique that uses conventional survey instrumentation as well as a specifically designed surface profile measurement apparatus. The profile data and survey observations are combined in a common least-squares adjustment model. The measured silo-wall imperfections are analyzed using a double Fourier series to determine dominant imperfection modes. The new silo and tank measurement technique offers many advantages over existing methods and has been successfully employed for the measurement of three large grain silos. Results from the measurement test are given as an example.