Previously we looked at static tower crane bases, however the most common tower crane base is a concrete pad with anchor bolts cast into the pad.
The process for making this crane base starts with the engineer. The engineer specifies the size of concrete pad and dimensions required, steel reinforcing and concrete strength. This varies depending on soil type (clay requires a bigger pad, sandstone and rock much smaller) free standing or ties in (free standing requires a bigger pad) the use of rock anchors (anchors can reduce the pad size required) and if the pad is in ground or only partially in ground or above ground (in ground is best)
This concrete pad was constructed for a 6 tonne Liebherr tower crane with a 50 meter jib.
Although the crane is fairly small, and the pad is on sandstone it required a huge pad.
A total of 50 cubic meters of 65 MPa concrete was used to make this pad.
The reason for the large pad was that it is not in ground but above ground and only supported by two sides. A much larger and more expensive option than a pad in ground, if pad in ground were used it would also of eliminated the need for using form work.
Knowlegable readers are probally wondering why 65 MPa concrete was used. The reason being the builder postponed building the pad untill a week before the crane was due to be erected. The engineer specified the concrete must be minimum 38 MPa. Concrete takes 28 days generally to reach its specified MPa. By using 65 MPa concrete it could reach 38 MPa (which it did) in one week not one month as would of been the case with 38 MPa.
Missed an article?
Type what you are looking for in the search bar or click on the archives