# Temperature growing Riks step ABAQUS

Hi all

I am modeling a truss in fire conditions, using ISO 835 fire for it. Now I have included some imperfections on the braces(L/1000) and I would like to know how to run this type of analysis(RIKS)

I used normally two steps, one to define the load on my truss and the second to import the temperatures as a predefined field. At this moment I do not know ho to modify my model steps in order to reach the solution. My temperature analysis takes 30 min and I cannot add time to a riks analysis

I am a bit lost, If someone could help me, I would be grateful to him/her.

### As you know, riks method

As you know, riks method doens't work with time. Therefore, if you temperature is varying in time at a rate that can not be described by some proportionality constant, Riks will be of much use here.

In case you temperature is proportionally changing, you define temperature load the same way as you would do in any other regular analysis. Any tempeature change will be considered as reference load in riks step, and will be changed as per load proportionality factor.

However, not that any property that depends on rate (e.g., creep, etc.) can not be accounted for in the riks method.

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The world started with 0, is progressing with 0, but doesn't want 0.

### Thank you very much Akumar.

Thank you very much Akumar. I have been trying to modifiy the order of steps. FirstlyInitial for BC I used 3 steps in the mechanical model: initial for BC, ona Static/general for the load and one Static/general for the temperature(predefined field with the temperature input on time)

What I have done now, is to change those steps into: initial for BC, one Static/general for the temperature(time depending) and one Static/riks for the load.

The problem now is the next: WarnBeamCurvature1 for some elements, since I have modified some braces of my structure and I gave them an imperfection of L/1000. Any other suggestions??

Thank you very much for all

Regards

Jose

### To understand what is

To understand what is "WarnBeamCurvature1" you need to understand what exactly abaqus does...for that read "abaqus analysis manual -> elements -> structural elements -> beams -> beam section orientation"

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The world started with 0, is progressing with 0, but doesn't want 0.