No abstract

An investigation was carried out to determine the response of an existing industrial plant to rod mill vibration. The disturbing forces and frequencies of the mill were estimated and compared with previous design and vibration measurements data on mill foundations. Owing to lack of space in the crushing area of the plant, it was decided to combine one of the building footings with the mill foundation. A dynamic analysis was carried out on the existing building to determine the structural response to the new mill vibration. The soil springs, geometric damping ratios, and rocking springs were calculated. Mill foundation and adjacent structures were modelled together using finite element dynamic program to calculate the natural frequencies, mode shapes, dynamic response, and amplification factors. Three design alternatives were considered. Based on the results of our analysis, one design was recommended to minimize the dynamic effect on the existing structure. The building structural system was altered accordingly. The new mill and the structural alternation were carried out during the spring of 1984. Since then, the new mill and the structure have performed satisfactorily. Key words: rod mill, foundation, vibrations, soil springs, dynamic analysis, structured response, dynamic amplitude ratios.

The present investigation deals with the removal of the lower portion of a glued laminated column in an existing uranium industrial processing plant in Saskatchewan, Canada. The lower 8 m of the column was eliminated to avoid transmission of high dynamic magnification forces created from installing a new rod mill in the crushing area of the plant. The construction details of transferring and securing the building column loads to the adjacent concrete wall and new steel trestle are examined. Some design aspects of a new built-up girder and other supporting elements are discussed. A summary of the construction procedure employed is given, which would be extremely valuable in similar structural alteration or rehabilitation jobs for old industrial plants. The construction of a new mill and the structural alterations were carried out during the spring of 1984. Since then, the new mill and the existing structure have performed satisfactorily. Key words: shearing existing column, rod mill, rehabilitation, built-up girder, structural alteration.