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 mid span is very small !!!
If I apply MEMEBER RELEASE (Fx) to the steel beams, the Mz moment would be correct, but what happents if I apply temperature load to the plate elements?
The axial force in the beams will be zero so this approach won't work properly.
I am really confused the way STAAD calculates section forces.
Do you have any clarification on this?
babmou
Hi Sureshprsharma,
Thanks for your reply.
I have used the EXPLICIT definition method in STAAD to create a composite beam.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 12-Oct-10
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 20 0 0;
MEMBER INCIDENCES
1 1 2;
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 2.17185e+007
POISSON 0.17
DENSITY 23.5616
ALPHA 1e-005
DAMP 0.05
ISOTROPIC STEEL
E 2.05e+008
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-005
DAMP 0.03
END DEFINE MATERIAL
MEMBER PROPERTY EUROPEAN
1 TABLE CM HE1000B CT 0.25 FC 55000 CW 8 CD 25
CONSTANTS
MATERIAL STEEL ALL
*
SUPPORTS
1 PINNED
2 FIXED BUT FX MY MZ
LOAD 1 LOADTYPE Dead TITLE LOAD 1
MEMBER LOAD
1 UNI GY -100
LOAD 2 LOADTYPE Live TITLE SHRINKAGE
TEMPERATURE LOAD
1 TEMP -30
PERFORM ANALYSIS PRINT STATICS CHECK
FINISH
The steel beam and concrete slab act monolithically and as expected for load case 1, the max Mz=5000 kNm, but it doesn’t work for the temperature load (Shrinkage).
I modified my model (Composite Beam.std) in such a manner you described, however I still get axial force in the beam.
Using OFFSET make the structure look graphically great but not statically.
Do you know a way to get around this?