Loadings imposed on the ground by cranes have been increased substantially. Large cranes such as the 1250mt capacity DEMAG CC8800 crawler crane can impose a pressure as much as 2.0Mpa on the ground. For these cranes, site preparation is required for heavy lifts. Site preparation usually includes placing mats under crane tracks to limit the ground pressure less than the allowable bearing pressure recommended by a geotechnical engineer. The current method of calculation of the allowable bearing capacity for cranes is based on the formulas used for spread footing and shallow foundation. However, there are differences in applying the traditional bearing capacity calculations for building foundations to a crane because the duration of loading for a crane is relatively short and the allowable settlements for cranes are higher. It is understood that total settlement is not a concern. Typically a crane can tolerate a maximum differential settlement of 1/200, which is much larger than 1/500 required for most buildings.; Computer simulation and field studies have been carried out to study the allowable bearing capacity for crawler cranes. A series of equations modified from the classical bearing capacity equations for foundations have been proposed for crawler cranes on different soils. A design procedure used to estimate the allowable bearing capacity for crawler cranes has also been suggested in the paper.
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