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Fatima, What has been stated above by Baz is very useful and you can use it for composite sections of any given configuration. Generally speaking, strength contributions by steel angles are very low and wouldn't add much to a concrete column section. I have used angles at corner of concrete section to allow welding of lighter items (like small pipes or cable trays) or to protect the corner from deterioration. I would suggest to ignore angles and don't rely on them. Now lets say you still want to consider the angles, for that case follow what Baz has said. So you can model a composite section or manually calculate the moment of inertia of combined section. By doing that, you can run analysis model and get your moments in the composite member due to the applied loads. Additional checks to do would be to make sure the bolts connecting the angles to the concrete don't fail before your angle attains yield strength. You can calculate the force in the bolts by using the Shear flow formula VQ/I. You will need to check different sections along the length as moment is changing constantly along the length. I hope this helps. Thanks.

One way will be to use sections designer in CSi softwares (Sap 2000, ETABS, Csi Col). Model four angles with re-bars by locating them at the centroid of of angles. You will have to define material for that reinforcement. This will be in addition to the existing reinforcement in the cross-section You can easily calculate the moment-capacity provided by four angles by manual calculation keeping in mind the crushing strength of concrete, and add it to existing capacity.

Thankyou all.. The people in this forum is always ready to help.. 😇