General In siting a tower crane for operation, particular attention should be paid to two factors: the crane standing or support conditions and the presence of proximity hazards. Consideration should also be given to the projection of the tower crane beyond the site boundary to avoid potential hazards to the public including those in private areas and public areas.
It is essential that the maximum pressures or forces which can be exerted by the tower crane on the ground or on other supports and tie frames are known. Tower crane manufacturers should provide this information or give a method and data from which it can be calculated.
Particular care should be taken in the assessment of wind headings, both operational and out-of-service. High winds exert considerable forces on tower cranes which are often sited in the vicinity of tall buildings. In such conditions, a generous allowance should be made for local wind pressures of high intensity due to funnelling (or venturi) and gust effects. Particular care should be taken in the design and details of all supporting structures, connections and anchorages.
The ground or foundations, temporary supporting structures, grillages, packings, connections and anchorages for tower cranes should be of sufficient strength to withstand the maximum in-service and out-of-service loadings without failure. In particular, suitable preparation of ground surface for fixed tower cranes should be carried out for safety reason. It is essential that the ground on which a tower crane stands has adequate bearing capacity. In assessing this, account should be taken of seasonal variations in ground conditions. The bearing capacity must not be exceeded under the most severe static and dynamic crane loading conditions. In a similar fashion, consideration must be given to the structural strength and stability whenever the unit is supported on or by any structure.