A recent article written by Geoffrey Goldberg and published in American Cranes & Transport emphasizes the importance of weight accuracy when planning for a lift. When planning for a heavy lift, it’s important to account for all aspects to ensure that you are not overloading the crane or the ground its set up on.
The objective is to ensure that the ground bearing pressure is always less than the ground bearing capacity, or in other cases lower than the maximum allowable ground bearing pressure that is dictated by the site owner.
If the ground bearing pressure is greater than the grounds bearing capacity the ground may will compress and compact to a point of support, or it may will continue to move, and potentially fail under the load and pressure. Many site owners provide a maximum allowable ground bearing pressure. This is generally speaking, this is not the ultimate ground bearing capacity, instead it is a self-imposed maximum allowable ground bearing pressure that limits the user.
DICA suggests customers establish an ‘everyday outrigger pad’ that should address 80% -90% of the lifting a crane is going to do; for critical lifts when more mat area is needed, customers can bring in additional matting to increase the area of contact and further reduce ground bearing pressures. “Always evaluate additional matting to determine if the matting has the strength to support the load and the rigidity to transfer the load to meet the stated requirements,” says Kris Koberg, CEO of DICA.