Opening In slab

[alex.romano8080]

Hi,

When I display the deflection maps of the slab, Robot does not show the opening but instead it shows how much the deflection in that area. In the real situation no deflection at all there!!

so Robot does not take into consideration the openings in the results?

Please Advise. 

[Krzysztof_Wasik]

Hi @alex.romano8080 

It is difficult to explain it looking at pictures only.

Robot should take opening into account while meshing and results presentation

Please share your model for verification. I will try to help

[alex.romano8080]

hi Krzysztof_Wasik,

Please find attached the zip file.

I think even in the calculation Robot did not take in consideration the openings, if you check the reaction at the bottom of column 10 you'll notice it as 1750 KN, but with hand verification i did not reach that value.

Thank you in advance. 

[Krzysztof_Wasik]

Hi @alex.romano8080 

There are no openings defined in your slabs. All openings which can be selected in Object inspector are defined in walls.

Blank regions presented for instance in slab 18 are caused by openings which probably existed but were deleted (issue in graphical presentation)

Presentation can be corrected by clicking right mouse button while slab is highlighted, selecting properties, closing meshing window and accepting and clicking Apply in Floor geometry dialog .

before

after

You have to define openings in slabs (Geometry >Objects>Polyline-contour)  and remesh slabs to take openings into account while calculation

Please accept problem solution on forum if my answer helped you

[alex.romano8080]

Hi Krzysztof,

but why in the 3 D view i can see the openings in the model? 

thanks 

[Krzysztof_Wasik · Accepted solution]

Hi @alex.romano8080 

It is issue in slab shading, after opening were removed. I have described it  in my previous mail together with correction steps- panel contour edition.

If you look closely and display finite elements, finite elements are generated inside those incorrectly shaded areas.

Since you do not have openings contours defined inside of slab, its interior will be meshed.

[alex.romano8080]

i got what do you mean Krzysztof_Wasik.

thanks you so much for your help. 

[alex.romano8080]

Hi Krzysztof_Wasik.,

Could you please help me out with the issue that I am getting regarding the cladding on the roof.

I want the rafters to get all the loads but some parts are not assuming any and get the error message in the calculation regarding them.

I have tried to design the cladding in all possible ways but no success.

I will be much thankful if you guide me out.

Thank you.

[Krzysztof_Wasik]

Hi @alex.romano8080 

If you use claddings they should be flat (all corners in one plane)

In your model not all are flat.

It can be corrected by Edit >Detailed correction >to plane

The other source of problem could be linear loads intersecting claddings edges. Linear loads should not intersect claddings edges. Robot cannot distribute such kind of load within cladding.

[alex.romano8080]

Hi Krzysztof_Wasik,

sorry to be pushy, but one thing to resolve in our case take days and you could save us lots time based on your experiences.

Could you please tell me how I could make a cladding in such roof to get the correct wind simulation and in the same time just the rafters will take the load.

by the way, since I ignore the main 2 beams, struts and bracing from cladding load, why the are making problem in the cladding load distribution. 

Thank You for the patient. 

[Krzysztof_Wasik]

Hi @alex.romano8080 

I am afraid I am not able to deliver general solution.

I am able to suggest way of model correction in that case.

After correcting roof geometry with detailed correction option (I have adjusted roof claddings geometry to 2 panes - cladding should be flat to transfer loads correctly)

And after deleting  linear loads in case 5 - linear load 0.14 on panel 564 edge

and    

case 10 - linear load 0.08 on panel 564 edge

Warning about load distribution disappears.

In my opinion problems in load distribution are caused by

• not flat roof claddings
• linear load defined on panel 564 edge, intersecting cladding 710 edge 

Attached you will find corrected file

[alex.romano8080]

Thank you  Krzysztof_Wasik,

much appreciated your effort. so kind. 

[alex.romano8080]

Hi Wasik,

I do not know who can help me in my case apart from you. Please when you have time could you please go through the model that you have already worked on. I have already correct the cladding issues and all concrete design is okay now.

I have reach the point that I should do the steel design but since i had lots problem with the bracing to make them as just tension due to instabilities type (1&2), so I have release them as per a video for Artur (i have called them bracing release).

My first question is I can run the calculation as static-linear and not Non linear since it took lots time and lots instability issues to verify the steel bars?

how i can if possible change the bracing to just tension without error?

Please, I need to submit this project could you please go through it and verify it so i can relay on the results especially for the steel.

Much Appreciated.

[Krzysztof_Wasik]

Hi @alex.romano8080 

I have opened your model and made the following modifications

• deleted bracing type releases from all bracing bars
• defined them as truss - tension bars only.

Model can be calculated without other changes.  Instabilities type 3  are reported. They can be ignored.

You can run model as linear model (without tension members). You will get compression in some bars but I do not expect big differences in other  (main members).

You can always compare results with model, modified according to above description and decide if it is necessary to wait for non linear results so long if you will have to modify model and repeat calculations.

While non linear analysis we are usually interested in results for combinations. So you can define simple load cases as auxiliary . They will be not calculated so it will speed up process a little bit.

[alex.romano8080]

Hi Krzysztof Wasik,

You are right 100%, I have change the bracing to tension only and after 40 min clicking to accept the type 3 instability, the result almost the same.

If I continue with linear analysis, the type of bracing release that I have done  (releasing Ry & Rz at beginning & Rx, Ry, Rz at the end) is still correct?

Technical question please, if you look to the rafters (80 & 129 typical), where in the real final project it'll be one piece connected from the main beam up to the wall, but in manner to connect the struts and bracing to it I have split it in the conjunction node. the problem that i have release it to have 0 moment at both ends wall & beam (real connection will be pin with no moment) but in this way I cannot release any more the struts to be pinned pinned and I am getting big deflection.

is this way correct? or I shouldn't split the rafter? 

A big Thank You for all your time and effort Wasik. 

[Krzysztof_Wasik]

Hi @alex.romano8080 

If you run non linear analysis press ESC to avoid accepting all instabilities warning.

Instead of using tension elements only you can use truss bars. Truss bars will work for tension and compression (linear analysis) and do not need any releases definition.

Regarding deflection in bar 80. 

You have defined the following system.

 Deflection mainly depends on longitudal 118 72 and part of 131 (14 m long) beam, release system and applied loads. (cladding has no stiffness). Those elements can be corrected to get smaller displacement. The simplest solution is to remove releases on elements 80, 81 (define it as continuous member) 

[alex.romano8080]

Thank You Wasik,

You mean to merge bars 80 & 81 as one beam? but these two beams will be connected through fin plate to the main beam 118 & 72. in this way i'll have moment there instead to have it as 0.

in the final real project will have beam 81 welded to bar 98 in the ridge going toward beam 118 & 72 to be connected trough a fin plate and the other part of it 80 & 129 will be one beam.

Could I have the 80 & 129 beams as 1 piece keeping the node 161 in place in manner to struts and bracing attach to it.

I couldn't translate the real situation in how I have make these connections and release.

Wasik, its to much asking but really i need a huge help.

much appreciated. 

[Krzysztof_Wasik]

Hi @alex.romano8080 

If it is finn plate connection it is better to define releases in connection. 

In that case displacements depends on 118 72 stiffness, span length and applied loads.

If there is no release between 80 and 129 it does not matter if they are defined as one beam or two separate members

[alex.romano8080]

Thank you so much Wasik,

I will apply what you have told me in all your answers hoping to do it correctly and get a correct result.

Much appreciated mate and you're doing a great job helping who's in need.

Keep it up.