hi prof. McKenna
in my model, when I use nonlinearBeamColumn element (force based), the internal force (axial,shear and bending) which I obtain from this command : ' recorder Element -file ele1local.out -time -ele 1 localForce' is acceptable. but when I change elements to displacement based nonlinear beam column,the internal force (in my model bending), is greater than the maximum plastic strength of element.in other word the output flexural force is grater then Mp=Z*Fy (Z is plastic modulo), is it possible to occur?
thank you so much.
disp vs force based nonlinear beam column
Moderators: silvia, selimgunay, Moderators
Re: disp vs force based nonlinear beam column
sorry i am not fully understanding the question so i give two answers:
1) the forces from the sections should not be greater than what the section will allow
2) equilibrium of the displacement beam will typically not be satisfied if you are using the element end forces and method of sections to check the internal forces at the sections or vis-versa to calculate the max forces at element ends given the section maximum. This is because the displacement element is a typical finite element, and finite elements only satisfy equilibrium in an average sense. If you want more agreement between section forces and what equi tells you should be there you have to discretize. The force beam column does not have this requirement.
1) the forces from the sections should not be greater than what the section will allow
2) equilibrium of the displacement beam will typically not be satisfied if you are using the element end forces and method of sections to check the internal forces at the sections or vis-versa to calculate the max forces at element ends given the section maximum. This is because the displacement element is a typical finite element, and finite elements only satisfy equilibrium in an average sense. If you want more agreement between section forces and what equi tells you should be there you have to discretize. The force beam column does not have this requirement.