Calculation of Stiffness constant
Calculation of Stiffness constant
(OP)
Hi All,
Does each and every different shape have its own stiffness constant value? For example will a PFC have a different K value to say a UB? If so is their a generic formula for the calculation of the constant for a given shape?
Cheers,
JohnOD1
Does each and every different shape have its own stiffness constant value? For example will a PFC have a different K value to say a UB? If so is their a generic formula for the calculation of the constant for a given shape?
Cheers,
JohnOD1






RE: Calculation of Stiffness constant
Yeah you are correct, each individual element does have its own stiffness coeeficient when related to others. Normally, for simple sub frames k (individual stiffness) can be related to I(second moment area) divied by L, length of element. For a continous member, I/L is multipied by by 0.5. So the stiffness of any element in subframe is its own stiffness divided by the sum of the stiffnesses of the other parts, at the given intersection.
At the higher end, Stiffness gets a bit more complicated, and is subject to a number of equation(my book reference for this is at work!!) but stiffness if a function of E, I and L. Let me know if you need more, and i'll try and help.
Andy
I'll let the big boy's tell me i'm wrong now!!!
RE: Calculation of Stiffness constant
RE: Calculation of Stiffness constant
If you ignore shear deformations, the stiffness of a cantilevered beam is 3EI/L^3 in bending, or EA/L in axial deformation.
Obviously PFC's and UB's have different second moments of inertia and area, so they will have different stiffnesses.
RE: Calculation of Stiffness constant
K = F/x
The 'F' and 'x' values would be obtained from the material's stress-strain mechanical properties at yield. Hope this helps,
-- drej --
RE: Calculation of Stiffness constant
I have new topic of interest: Blast Overpressure Loading on industrial structures.
Can anyone guide me to some useful books/web sites that could provide the basics?
Regards,