05-21-2012, 07:29 AM
Anyway my problem is about Slenderness of a pile. My superior had instructed me to investigate the buckling load capacity of a pile having an unsupported length of 19.21 meters. Loads and other design data are follows;
Factored Axial Load= 388.42*1.2 + 324*1.6 = 984kN
Compressive strength of pile = 41.4 mPa
Factored Dead Load/Over Total Factored Load can Conservatively taken as 0.6 (this is the term Bdns using ACI code)
Hence, the Stiffness is Equal to 0.25*EcIg
Euler's Formula is Equal to pi^2 EI/(klu)^2
k is determined by the design Engineer equal to 0.75.
The pile is 450mmx450mm in dimension with 10-12.7mm standard prestressing strand in circular pattern with steel grade of 1862 mPa having a clear cover of 100mm for marine structure and 10mm spiral diameter.
We know that the capacity is very high considering this as short column, but taking into account the slenderness of the pile, it seems that the capacity will abruptly change depending on the Effective Length (klu) of the pile. Now, do I need to reduce the computed buckling strength by using a factor of safety of two or less for the buckling strength when I follow the Strength Design set by ACI code for Slender Columns???
Any comments and suggestions is highly appreciated.
Regards,
Lambert
Factored Axial Load= 388.42*1.2 + 324*1.6 = 984kN
Compressive strength of pile = 41.4 mPa
Factored Dead Load/Over Total Factored Load can Conservatively taken as 0.6 (this is the term Bdns using ACI code)
Hence, the Stiffness is Equal to 0.25*EcIg
Euler's Formula is Equal to pi^2 EI/(klu)^2
k is determined by the design Engineer equal to 0.75.
The pile is 450mmx450mm in dimension with 10-12.7mm standard prestressing strand in circular pattern with steel grade of 1862 mPa having a clear cover of 100mm for marine structure and 10mm spiral diameter.
We know that the capacity is very high considering this as short column, but taking into account the slenderness of the pile, it seems that the capacity will abruptly change depending on the Effective Length (klu) of the pile. Now, do I need to reduce the computed buckling strength by using a factor of safety of two or less for the buckling strength when I follow the Strength Design set by ACI code for Slender Columns???
Any comments and suggestions is highly appreciated.
Regards,
Lambert