Input file for simple rigid plane frame analysis

[ankitk]

Good day,

I am having issues creating an input file for a simple rigid plane frame analysis. I am attempting to replicate a text book problem (see image attached) and have created the attached input file. I am unable to replicate the results calculated by hand or provided by the text book. Any assistance in correcting my input file would be greatly appreciated.
Thank you.

[Prof. R.L. Taylor]

Look in the output file at the element type you are using.  It will say linear displacement with shear.  The textbook uses cubic displacements for bending and does not have shear deformation.  If you add
SHEAr OFF
to each of the materials you should get the correct answer.

Hint: Always look at the output file, especially the output of material data which gives a lot of information besides the modulus and Poisson ratio.

Also it is known that FEAPpv has errors in the 2-d frame elements. Updates will be made to files in December to correct the known problems.

[ankitk]

Thank you for the quick response sir. That did solve my issues, I am currently using FEAP 8.5.

I was wondering if it is possible to output the nodal reactions using the global coordinate system rather than the local system used to analyze the reactions at the node? As well, anytime a cross section is changed (for example thickness) does a new material need to be defined or can they be defined for the specific element?

[Prof. R.L. Taylor]

When you output reactions with the command REACtion ..... the values are in global dof directions.

Currently, FEAP does not separate the cross section properties from the material properties, thus you would have to use a different material for each cross section.   You could change this by adding an array with cross sections and then modify the element you use to use these instead of values from the "d(*)" array.

[ankitk]

Thank you! I had a few follow up questions with regards to 2D frame elements.

I am trying to recreate the attached 3D problem in 2D. I compared the FEAP output to ANSYS and it seems to be correct. ANSYS provides the same results when the geometry is set to 2D, as all the Z coordinates are zero.

I have tried to recreate it by utilizing either CROSs SECTion info (area and inertia) and SECTion CIRCle (radius and quadrature). However the values determined when utilizing the CROSs SECTion info are higher in magnitude than the response determined by the 3D solution. When utilizing the SECTion CIRCle input the deformation is opposite to the direction of the load.
If you could provide some guidance that would be greatly appreciated.

Once again I would like to thank you once again for your assistance. I am currently learning FEA on my own time and utilizing FEAP for a course project in optimization.

[ankitk]

Thank you! I had a few follow up questions with regards to 2D frame elements.

I am trying to recreate the attached 3D problem in 2D. I compared the FEAP output to ANSYS and it seems to be correct. ANSYS provides the same results when the geometry is set to 2D, as all the Z coordinates are zero.

I have tried to recreate it by utilizing either CROSs SECTion info (area and inertia) and SECTion CIRCle (radius and quadrature). However the values determined when utilizing the CROSs SECTion info are higher in magnitude than the response determined by the 3D solution. When utilizing the SECTion CIRCle input the deformation is opposite to the direction of the load.
If you could provide some guidance that would be greatly appreciated.

Once again I would like to thank you once again for your assistance. I am currently learning FEA on my own time and utilizing FEAP for a course project in optimization.