I am using the composite beam design capabilities. But the output does not show any evidence of this design. Why?
There are 2 sets of data associated with analysing and designing a composite beam.
Step 1 : Define the member properties as a composite beam. To do this, one has to use the "TA CM" option as explained in the Help Section TR.20.1 Assigning Properties from Steel Tables. For example, if member 1 is a composite beam made up of a 3.0 inch thick slab on top of a W18X35, and the grade of concrete is 4.0ksi, one would have to specify
UNIT INCH KIPMEMBER PROPERTIES1 TA CM W18X35 CT 3.0 FC 4.0
Step 2 : Parameters for steel design. This is what you find in the STAAD.Pro Help Section Design > D. Design Codes > D1. American Codes > D1.B. American Codes - Steel Design per AISC 9th Edition > D1.B.1 Working Stress Design > D1.B.1.7 Composite Beam Design as per AISC-ASD. These are the attributes which are to be used in the actual design equations, using the expression PARAMETER, as in,
PARAMETERCODE AISCBEAM 1 ALLTRACK 2 ALLFYLD 50 ALLCMP 1 ALLDR1 0.3 ALLWID 60 ALLFPC 4 ALLTHK 4 ALLSHR 0 ALLDIA 0.75 ALLHGT 4 ALLRBH 2 ALLCHECK CODE ALL
The most important thing to note here is the usage of the parameter CMP. Unless it is set to 1.0, STAAD does not design the beam as a composite section. The beam will be designed as a pure steel beam section in the absence of the "CMP 1" parameter. These parameters are available for the AISC 9th Edition only.