Chord-rotation hand calculation

[Giosmi]

Hello,

i was trying to reproduce by hand the calculation of the ultimate chord-rotation capacity of RC elements (beams and columns) by NTC2018, that is equation 8.7.2.1.

Following costant and timestep properties in the Detailed Calculations(Annex) tab of the Print‐out Options module of Seismobuild for Example 1, i noticed two things:

1)in the Detailed Calculations Annex, the Area of trasversal reinforcement "As" is calculated as the area of a single stirup bar, even though it is written as "As = Astir*ns", with "ns = No of stirups". Please, check it

2)The ultimate chord-rotation capacities differ for a factor of 21.54% for beams which "actual" cross sections are not rectangular (following the properties and intermediate results of the Annex). What i mean is: trying to simply multiply all the numbers found in the annex (as equations 8.7.2.1) for these class of beams, the ultimate chord rotation found in the annex is always bigger of 21.54%.
The ultimate chord-rotation capacity i calculated for other elements, as columns or rectangular beams, matches perfectly (following the annex).

Is there a coefficient that has not been put in the annex that multiplies the whole ultimated chord rotation capacity in these cases? Why is there such a difference?

Thank you

[z.gronti]

Dear Giosmi,

The first issue that you mention, is just a typographic error and it will be fixed in the next release of the program.
As far as the second issue is concerned, i am not sure that i understand the meaning of "actual cross sections are not rectangular". However, i cannot duplicate the difference you mention. Do you use the current v2023 of the program?
Could you please send me an email at z.gronti@seismosoft.com with the file you checked, the specific element you checked and showing the values in the report that you have the reported issue?

[Giosmi]

Dear Zoi Gronti,

sure, I will send you everything.

Thank you
Giosmi

[z.gronti]

Dear Giosmi,

As i informed you via email, the problem with the difference you reported has to do with the fact that you haven't taken into consideration the proper h and b values for the axis you were checking.