Cervenka Consulting Forums — modelling RC beam using shell element

Re: modelling RC beam using shell element

null@example.com (dpryl) — Wed, 19 Feb 2014 16:47:07 +0000

Then, you can send us your model, following the instructions in ATENA Troubleshooting, 2.1.1 I have a problem not listed here.

Re: modelling RC beam using shell element

null@example.com (mtma) — Wed, 19 Feb 2014 14:54:11 +0000

Dear dpryl

I read ATENA Troubleshooting, 2.2.6 but I still can't figure out the problem!

Re: modelling RC beam using shell element

null@example.com (dpryl) — Wed, 19 Feb 2014 13:20:13 +0000

Dear mtma,
please see ATENA Troubleshooting, 2.2.6 Floating point problems - Division by zero, Loss of >7 digits on the matrix diagonal, Warning: Sign of diagonal changed when reducing equation, Floating point exception: Multiple floating points traps, Zero or negative jacobian, InvertA: zero determinant, CCMaterials Extended AExc: CC5ParamYield F:project_stress_on_f_division by zero, and similar

Re: modelling RC beam using shell element

null@example.com (mtma) — Wed, 19 Feb 2014 11:10:08 +0000

Dear dpryl

during the analysis of the previous beam, the following message appears:
Warning: Sign of diagonal changed when reducing equation(****).

What does this mean and how does it affect the results?
Thanks

Re: modelling RC beam using shell element

null@example.com (dpryl) — Tue, 18 Feb 2014 09:43:10 +0000

Dear mtma, please see ATENA 3D User's Manual, 3.7.2.2.7 Shell Macroelements (if you work in ATENA Engineering 3D) or ATENA-GiD User's Manual, 5.3.2 Shell Material (if you use the ATENA-GiD interface of ATENA Science) for basic information about defining shell elements.

A quaote from the ATENA-GiD User's Manual:
Unlike volume elements, a single shell per volume thickness works well in bending. In other words, placing 2 or more shell elements above each other ("above" refers to the shell thickness direction) is not a good idea. Instead, use a single shell per thickness with more internal layers to improve precision.

I would further recommend to read ATENA GiD User's Manual, 5.7 Finite Element Mesh or ATENA 3D User's Manual, 3.7.4 FE Mesh for general information about meshing in ATENA.

modelling RC beam using shell element

null@example.com (mtma) — Mon, 17 Feb 2014 15:43:41 +0000

Dear Sir,

I'd like to model a RC beam using shell elements, the beam depth is 0.55 m. Should I use a mesh size of 0.55m or can I use, for example 0.05m?. Because when I did so an error occurred saying that there is more than a single element layer in local Z direction.