Topic: Model of a Simple axial loaded column doesn't work

Hello,

I want to model a reinforced concrete column with an increasing axial force until a specified load. I modeled the column with smeared reinforcement and add two steel plates to the ends, one for applying the axial load and the other for applying boundry conditions. I apply a point force to the middle of the plate. It seems so simple!
However, when I run the model  at the very first step I come to many errors and warnings as :

(*)    Warning: Loss of at least 7 digits in reducing diagonal of equation: 1762, (node: 3021, dof_id: 1); value: 179383
(*)    Warning: Loss of at least 7 digits in reducing diagonal of equation: 1768, (node: 3003, dof_id: 1); value: 100136
.
.
.
(x)    CCMaterialExtendedAExc: CC5ParamYieldF::project_stress_on_f - division by

Could anyone provide some comments to solve the problem?
Respects

Re: Model of a Simple axial loaded column doesn't work

Dear Mehdig84, please see ATENA Troubleshooting, 2.4.6 Floating point problems - Division by zero, Loss of >7 digits on the matrix diagonal, CCFEModelExc: CCPardiso solver error: zero pivot,  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.

If you still can not identify the problem source, you can follow Troubleshooting, 2.1.1 to send us your model etc.

Regards.

3 (edited by Mehdig84 2018-11-09 10:24:16)

Re: Model of a Simple axial loaded column doesn't work

Dear DPryl,

I appreciate your response. Actually I found the solution. I clarify the solution so that it may be used by others.
In my Model I have two loading conditions. The first one is a point load applied to a particular amount and then kept constant. While the force is constant a prescribed displacement starts to be applied. My mistake was that I didn't aware that in both conditions Supports must be present (I didn't include the support condition in Force Interval and that was resulting the model to be unstable). Now I correct the analysis by including the first interval with Force and Supports and the second interval with Prescribed displacement and Supports.



Now the problem that I faced is how in GiD the load cases should be chosen. The only thing that I found is "Add Additional Load Cases" option available in recent version of ATENA-GiD Interface(Atena_GiD541_15728). But how the id should be chosen for a load case. Is there any way to obtain the id for a load cases in GiD? There is not enough description for this option.

Yours Sincerely

Re: Model of a Simple axial loaded column doesn't work

Hello,

each interval creates a load case... first interval creates LoadCase 1, second, LC2, ...

so if you can use the load from interval 1 in interval 3, you need to uncheck "Delete BC data after calculation" in interval 1,
and use LC1 in Add_Additional Load cases in interval 3

BR Zdenek