negative torsional rigidity

[Muntasir]

Hi,

I am modeling a steel frame with hollow steel sections. When I run the model it shows a message negative torsional rigidity for section ID 4 and then the analysis stops. What might be the possible reason behind this and how this can be solved.

Thanks for your help.

[Stelios_Antoniou]

This seems to be a bug of the program. Can you please send the project .spf file to support@seismosoft.com? Thank you.

Seismosoft Developer

[Muntasir]

Hi Stelios,

I have sent the model.

Thanks

[Stelios_Antoniou]

We checked your file and it appears that there was no bug in the calculations of the section properties, however there was a lack of proper checking by the program.
The unfriendly message was caused by the zero values that you introduced in the top flange thickness and the top flange width of section 35, values that are not permitted. Please, adapt the section by introducing values larger than zero for the top flange (e.g. by reducing the height of the web and introducing a flange of width equal to the web thickness).

Seismosoft Developer