The Orientation depends upon the direction of applied load. we will get maximum capacity out of a Cantilever beam /Simply supported beam  If we place it web vertical  position parallel to loading direction, as the section modulus(Zxx) in this orientation will be maximum.Bending Stress will be minimum.But the same I section will be placedWeb horizontal to take on the wind load on the Gable or Side Wall of a Workshop Building.

You first should explain the types of loads the beam will bear. In this answer I'll assume it will support vertical (gravity-induced) dead and live loads and that the beam is oriented so that flexure occours in the direction of maximum bending resistance (section modulus) of the beam . Then you need to state the type of the member you want the beam to be connected to. If the connection is between a secondary beam and a principal beam, one of the most typical connection is a hinged one realized using 2 short L-shaped profiles bolted to the webs of both the principal beam and secondary beam. The main reasons for this choice are: ease of realization (no welding required at all), a real behaviour that is a good approximation of the desired (ideal) hinged connection and quite generous production tolerances allowed for the assembly if compared to alternative solutions.

Dear Fedrico

I have answered the question to justify that Orientation depends on direction of load irrespective of type because Ixx is maximum if u place it parallel to load.I think you have missed the question..You have gone to connection details which is not connected with orientation.

Dear Mrigenta Nath Ray,

I was not referring to your answer which is 100% correct.

I was answering the original question by also giving details on a typical beam-to-beam connection. I believe that the original question is not very clear. It does not explicitely ask for the best orientation. If the problem was only what's the best orientation, then, as you said, what governs the design is the direction of the load on the beam irrespective of the static configuration. So I assumed that maybe the original poster was asking for something else, i.e. which is the best way to "connect" (instead of "mount") a simply supported I-shaped beam. Hope this clarifies why I added my answer. Kind Regards.

Okay its fine.Best Regards

Thanks a lot both of you (Dear Mrigendra nath Ray and Massimo Federico Bonfigli) sir and sorry for inconvenience.

Actually this question was asked in my personal interview.

Interviewer asked me that how should you mount an I cross section beam irrespective of orientation??? And hasn't clarify the type of load and other parameters(conditions).

So irrespective of orientation what should be the best way to mount an I cross section beam??