Concrete Beam Design

I am fairly new in structural engineering, so I hope somebody could help me out with this simple problem that I have:
I have a grade beam bearing @ 2 ends on top of footing.
Should I design it as a "fixed-fixed" condition? or a simply supported condition?

Help and please pardon my knowledge in structural engineering.

 

[dison]

I am not sure of your loading conditions for this grade beam supported on two footings, so I cannot give an opinion on which way would be the best way or required way to transfer the given loads. However, I can give a general response based on a general design of beams.

You can design it either way. Which way depends on how you want and expect the beam to behave under loads. Just make sure that you design the beam the way you analyze it. For example, a fixed-fixed beam would need to have adequate moment capacity at the ends and adequate ability to transfer the moment to the support. This condition, in turn, would affect the loads to design your support. A simple beam would need to have end conditions that allowed rotation and do not develop or transfer moment.

Hope that helps. ~dison

 

[jeg]

Consider the scale of costs:
-concrete and rebar are low cost
-manhours are expensive
-supervision is very expensive (complexity requires more supervision)
-mistakes are extremely expensive.

Keep your design as simple as possible within the parameters imposed; this reduces the need for supervision and the possibility of mistakes in design and on site.

In general separate bases are less costly than combined bases and simply supported beams are less costly than beams with fixed end moments.
Fixed end moments introduce extra cost and complexity into the beam and into the bases.

In general, complexity is only justified for external constraints such as limited space or architectural requirements.

Good luck and welcome to the profession.