Composite beam in STAAD

[Bill2001]

Hi,
I am trying to model a composite beam (steel beam + concrete slab).
For this purpose I modeled my composite beam as a steel beam and plate elements.
I applied then an offset distance 0.95 m to the steel beams.
Now I see that the steel beam gets a very large axial force and the Mz moment at the mid span is very small!!!
I am really confused the way STAAD calculates section forces.
Do you have any clarification on this?
Do you have any sample for a composite beam used in STAAD (built-in Composite Deck)? Could this feature used on user defined beams such TAPERED?
I have uploaded my input file.

Thank you
Bill

 

[Bill2001]

Ed,
Thanks for your help.
Could you please say why I have to change the support?
Bill

 

[edward1]

Because that is where the support should be! I have attached a design of this using Digital Canal Composite Beam which limits the deflection to L/800 for live load.

 

[Bill2001]

Ed,
Thanks for your helps!
I don't know why we should model the structutre this way.
Don't you think this is a limitation in STAAD?
When you use Digital Canal Composite Beam, do you also get so large axial forces in the girders?
BTW I see you are an advanced user of STAAD using REPEAT in your input file.

Bill

 

[edward1]

Bill,
I agree that this is a stretch for STAAD. The Digital Canal Composite Beam program is much easier for this problem.
Ed