Composite Column Design:Shear resistance

[cecil123]

For a composite column section:

The design shear resistance (?RD) due to chemical bond and friction is limited to the following values (as per the EuroCode4):

1)For fully concrete encased I sections: 0.6 N/mm2
2)For concrete filled hollow sections: 0.4 N/mm2
3)For flanges in partially I encased sections: 0.2 N/mm2
4)For webs in partially encased I sections: zero

I do not understand the last two point??
What does it mean by "For flanges in partially I encased sections" and "For webs in partially encased I sections"

Please help!!!

 

[WillisV]

Partially encased composite columns are columns where the concrete is only formed out to the tips of the steel section flanges (so that the width and depth of the composite section is the same as that of the steel section, you are just filling in the open space in the "I" shape with concrete).

The code is saying that you only get to count on the bond stress developing for the concrete surface against the inside flanges of the steel section and are not allowed to use any bond strength for the surface against the web of the steel shape.