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I need just little bit of confirmation about what I'm doing.

Normally I know how the stiffness matrix is composed for 2 node frame element in 3D space. which creates 12x12 matrix for that element, if there is also thermal loading on frame element additional coefficients(Q_{12x1}matrix) will contribute to the RHS of KxU=F equation.

Q=TRANSPOSE(\begin{bmatrix}Px1&0&0&0&-My1&Mz1&-Px2&0&0&0&My2&-Mz2\end{bmatrix})

where

Px = E*A*[itex]\alpha[/itex]*ΔT

My = [itex]\int \alpha[/itex]*E*ΔT*z*dA

Mz = [itex]\int \alpha[/itex]*E*ΔT*y*dA

Is this the correct formulation of 3D frame elements thermal coefficients matrix?

Frame stiffness matrix works flawlessly, but if I introduce the Q on the right side of linear equations I always get the wrong solutions. The process itself is so simple but couldn't spot what I'm doing wrong.

Your help will be appreciated,

Regards,

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# 2-node Frame FEM element thermal formulation

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