# Material Parameters (Pipe Pile Wall with Strengthening Plate)

Dear All,

Im facing a problem about assigning the parameter of pipe pile wall with strengthening H-pile and Plate in my Plaxis 3D (Plate element)

Section is shown as below:

the spacing is 800mm centre to centre and bending in strong axis.

How Can I model this type of pipe pile wall with the following parameters?

Thank you.

William

Parents
• Dear William,

A very nice question indeed.
In this case, I would compute the equivalent stiffness and flexural rigidity (EA and EI) for a single section for both the stiff bending direction and the soft bending direction.
The issue here is that PLAXIS 3D assumes geometric isotropy with the stiffness being isotropic or orthotropic.
In the manual, there is some guidance on how to deal with this for a T-shaped concrete floor profile.

Basically you should try to match the important bending direction for your plate. If I assume this is the bending of the 1 axis, you should make sure that E1 = 12* (EI)_eq / d^3 (with d the one you fill in) is correct. Then try to match (EA)_eq = E1 * d. Next would be to find the same for the EA and EI in the soft direction. Since you model these as plates, some assumptions would be necessary.

By the way, will the H beam have a 100% bonding with the grout? If this is not the case, please make sure to adopt this in your EI value, or set a limit for the capacity.

Answer Verified By: William Lau

• Dear William,

A very nice question indeed.
In this case, I would compute the equivalent stiffness and flexural rigidity (EA and EI) for a single section for both the stiff bending direction and the soft bending direction.
The issue here is that PLAXIS 3D assumes geometric isotropy with the stiffness being isotropic or orthotropic.
In the manual, there is some guidance on how to deal with this for a T-shaped concrete floor profile.

Basically you should try to match the important bending direction for your plate. If I assume this is the bending of the 1 axis, you should make sure that E1 = 12* (EI)_eq / d^3 (with d the one you fill in) is correct. Then try to match (EA)_eq = E1 * d. Next would be to find the same for the EA and EI in the soft direction. Since you model these as plates, some assumptions would be necessary.

By the way, will the H beam have a 100% bonding with the grout? If this is not the case, please make sure to adopt this in your EI value, or set a limit for the capacity.

Answer Verified By: William Lau

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