Shear Area and Class for sections

[jbervel]

Hi,

we are developing an application with Robot, and we have a problem with cross section parameters when we create a new profile.

We use the Section Database to create a new profile. We introduce all the parameters associated to the profile, and we have a problem with the parameter "Type" that we are going to try to describe hereafter.

If we put this parameter to zero (unknown shape profile), after calculations we have found that class of this section is always 1.

If we associate another value to "Type" (C_USER shape profile) then, after calculations, the profile class is ok but the shear areas do not match with the values from the database (it looks like the program calculates these values internally).

Is there any way to associate the correct class and shear ares to a new profile?

Thanks in advance.

[waldemar.okapa]

Use the built-in standard section TYPEs. Program will not recalculate the parameters. Brief description from help attached.

[jbervel]

We have tested your solution but it has not worked.

We have used a standard section shape type: I_BSST_COLD_SIGMA1 with id 1001. This one is a cold formed profile.

Robot has assigned section class 3 but the shear area (Ay and Az) has been modified in the dimensioning stage.

Furthermore, if we do not associated any section shape type to the profile, Robot always considers it as class 1, with the correct shear area values.

We do not know where is the problem, maybe we are doing something bad.

Do you have any idea?

Thanks

[waldemar.okapa]

The section class is recognized according to the design code, on the basis of section shape (TYPE) and dimensions. So the proper shape type must be defined in the database.

The shear area reported in the steel design results is the effective shear area calculated according to the code rules. So it is possible that it can be different from that defined in the database.

Steel design codes define specific rules for the section class or the effective shear area.

[jbervel]

So, if we associate any shape type to our profile, the shear area used for calculations will be different from those introduced in the database?

Does Robot calculate the effective parameters for class 4 sections automatically with the same parameters from the shape type chosen?

We know that we can not modify the parameter thin-wall section from the API, but if we modify it directly in the database field, has it any influence in the calculation?

As we indicated in the first message of the thread, we have also tried to leave in blank the shape type field, and we have found that Robot exports the shear area parameters correctly, but it always associate the same section class: class 1.

From your answers, we guess that if we have a class 4 section with a different shape type from those used in the database, there is no way to match the class type, effective properties and shear areas for the calculation of a cold-formed profile, is this ok?

Thanks

[waldemar.okapa]

You ask very specific questions. Better write to adsk service who is able to consult the answer with the developers.

But actually there are different rules for effective shear area according to EC or BS code. There are different rules to define class type for I section or a cold formed profile.
If you do not define the shape type you will always get class 1, the program is not able to read your mind.

[jbervel]

But we have shapes differents from the ones defined in Robot.

If the program would be able to read parametric shapes we would not need a program that can read the mind.

Anyway thanks by your support.