Tower Crane Foundation Design- Accounting for Torsion
Tower Crane Foundation Design- Accounting for Torsion
(OP)
I am working on a design for a spread footing foundation system for a Liebherr 630 EC-H 20 Litronic tower crane. I am wondering how to design for the torsion that would be expected from this type of crane. I have the value for the torsion created by the crane when in operation. Any tips or references to get me started would be great.





RE: Tower Crane Foundation Design- Accounting for Torsion
If you're worried about attachments, that's a different calculation.
RE: Tower Crane Foundation Design- Accounting for Torsion
Also pls see
http://ssi.civil.ntua.gr/downloads/journals/1991-A...
http://www.etcg.upc.edu/docencia/postgrau/mobilita...
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
An altrnative would be to use the Gazetas impedance method, since the twisting moment which means IAstatengineer is the same torsional impedance in Gazetas article.
I would model an elastoplastic spring, that is, until a certain rotational displacement is reached we are in the serviceability field, then we reach the ultimate state of plasticity hence soil collapse.
Dynamic torsional stiffnes for a square footing would be Kt= 8.3*GB3 [kN*m],where G is operational shear modulus and B side of square footing. This is a lower bound solution since no embedment is considered.
I find this interesting because I've never dealt with torsional moments. The engineer should choose a critical acceptable rotational displacement (in radians) beyond which we have plasticity or unacceptable strain. Theta=Mz/Kt.
According to you guys, which would be a critical treshold for rotational displacement theta in our crane example?
RE: Tower Crane Foundation Design- Accounting for Torsion
Of course, if your tcf is supported on piles, you can pass the torsion directly to the piles as shear.
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
RE: Tower Crane Foundation Design- Accounting for Torsion
With a secant G of 30000 kPa (4351 psi), which is not a rigid soil and a 3 m (9 feet) square section footing, I get a 1*10-4 radians of rotational deformation, which definitively doesn't sound critical, and this without an embedment.
Unless I'm seriously wrong, this may be why the torsional moment does not govern design unless it's extremely large.
I'm kind of nonplussed because I was expecting a larger deformation...