Section Moment of Shell Element in Abaqus

[Yochael1996]

Hi all,

I am facing difficulty to read the Section Moment from Abaqus.
I am designing a bridge deck, and I want to get the moment effect from Abaqus. I modeled the deck using Shell Element, and the bridge girder is along Y-axis so that I anticipate that I should read the section moment in the y-axis (i.e. SM2).
However, the value does not make sense, not even in the correct order. I guess the problem may be the unit. From the user manual, the Section Moment is the "moment per unit length". Can anyone tell me how to convert the "moment per unit length" to the moment that design engineers usually use (kip-ft, lb-in, etc.)?

Thanks in advance!

 

[FEA way]

This variable is defined as section moment per unit width. Thus its unit in SI system is Nm/m. And if you want to get the value in Nm you have to multiply it by the width.

 

[Yochael1996]

Hi FEA way,

Thanks so much for replying. Would you mind take a look at the attached picture? If I want to get the moment in the y-direction, should I use the SM2 value times the shell element thickness?

Thanks again!

 

[FEA way]

With shell elements it's not that easy since they use local CSYS following special convention. SM1 is bending moment per unit width about local 2-axis, SM2 is bending moment per unit width about local 1-axis and SM3 is twisting moment per unit width in local 1–2 plane.

 

[Yochael1996]

Hi FEA way,

I am still confused. How does the "local CSYS" system work? For example, for this specific case, how can I get the moment in the y-direction in terms of in-lb or kip-ft or whatever (i.e., how can I get the integrated bending moment about local 1-axis)?
Sorry for the confusion. It would be greatly appreciated if you could follow up on this problem.

Thanks!

 

[FEA way]

In this particular case global Z direction is normal to the shell surface so after projection local directions will be the same as global ones.

 

[Yochael1996]

Hi FEA way,

Thanks for replying!

Regards,
Yochael