panel issues

[lowryder]

Hi,

I am modelling a 4 story RC shell structure (shear walls) and I am facing the following problems.
1. The dynamic analysis is performed as usuall but after that when I run the Required Reinforcement for the panels I get As=0 for the walls and As=min for the slabs. I have attached the model.
2. In case I want to check the interface shear in the bottom joint between wall and slab I have two options (If I am not wrong) either introduce a panel cut and check the values or obtain the values from the reduced results on panels
    for the specific cut. The question is which value would give me a quantity for the interface shear at the joint? I assume the TRz is the shear force and tR the interface shear. Why there is no quantitative matching between the values of the panel cuts and the ones from the reduced results see picture?
3. I am aware that robot has the option of the rigid diaphragm for the floor. Since I have RC floor I have to denote it as a rigid diaphragm or it is already calculated as rigid due to its material properties (RC)?

Any ideas/suggestions would be appreciated!

Since the zip model file is more than 1,5 MB I provide an external link http://www.sendspace.com/file/bq0uxn

thanks
Kostas

[Artur.Kosakowski]

1. This is due to code requested level arm which determines required area of reinforcement. In Robot this is the part of the minimal reinforcement area calculations.

2. See the attached picture

3. The stiffness is based on thickness assigned to the panel/ The rigid diaphragm calculation model is intended for not meshed floors.

Please be aware that Robot 2009 is no longer officially supported. The screen capture is from Robot 2014.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[lowryder]

Thank you Mr. Kosakowski for your answer.

I am fine with the third question but I am not sure what to do regarding the first two.

1. The thing is that I get zero required reinforcement for the walls and the minimum for the slabs. Thus I cannot provide any reinforcement and design proposal for the panels. I recall that in a previous run I got required percentages of As....after that I did some changes to the model and I end up with this problem.

2. Ok the matching of the values between panel cuts and reduced results is clear. One last thing, is tR the interface shear stress of the joint between wall and slab (see attached image)?

Kostas

[Artur.Kosakowski · Accepted solution]

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1. The thing is that I get zero required reinforcement for the walls and the minimum for the slabs. Thus I cannot provide any reinforcement and design proposal for the panels. I recall that in a previous run I got required percentages of As....after that I did some changes to the model and I end up with this problem.

I really like the questions of  'I did something and now you figure out what it was' type  .

Let me try. My assumption is that in Job Preferences/Structure Analysis/Seismic Analysis you marked save of the results of quadratic combinations only with the projection of the results on the automatic direction having the main direction of reinforcement for walls set as direction Z. You have two options: 

- set the direction of the main reinforcement for walls as automatic setting the local X of walls as vertical and calculate reinforcement again

- switch the save of the results of quadratic combinations off and calculate the model and reinforcement again

As you indicated only quadratic combinations in the calculations of required reinforcement for slabs the forces in slabs are too low to have more reinforcement than minimal.

2. Ok the matching of the values between panel cuts and reduced results is clear. One last thing, is tR the interface shear stress of the joint between wall and slab (see attached image)?

I'm not sure if I understand you correctly. Please check 

http://docs.autodesk.com/RSAPRO/2014/ENU/filesROBOT/GUID-3936FDA3-5DFD-4F31-B16A-F0208A451282.htm

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.