reinforce concrete beam design

[aldincrump]

how is a reinforce concrete beam design that is fully supported along it length for example the beam is resting on a masonry foundation wall

 

[MIStructE_IRE]

What is the beam doing? A sketch might help clarify.

 

[aldincrump]

 

[bob33]

Maybe the soil is poor and the designer wanted to even out the differential settlements and avoid diagonal cracking of the masonry. A continuous spreader beam can be designed assuming a continuous support (in this case variable spring supports based on discussion with geotechnical engineer) or can simply be designed to span a certain distance based on experience. Maybe the beam depth was chosen because the designer wanted to see an exposed concrete foundation above grade.

 

[hokie66]

More likely the last sentence in bob33's post applies. But structurally, the concrete is just part of the wall.

 

[hoshang]

how is a reinforce concrete beam design that is fully supported along it length

A beam is a flexural member which carries loads primarily by bending. In your case the member can't be classified as a beam (at least in my thought). Your member (as you called it a beam) may be useful for reducing height of masonry or waterproofing (provided the concrete is mixed with sika or any waterproofing agent).

 

[aldincrump]

Bob33 are you thinking of the design of a beam on an elastic foundation
Wingler etc

 

[bob33]

Aldincrump, yes I was thinking of a Winkler design except the spring constants (k values) would vary depending on the amount of differential settlement really expected. Personally, when the soil is poor, I have always used full height reinforced concrete foundations and designed them for a certain span depending on the circumstances.

 

[haynewp]

Are there deep foundations beyond the grade beam?

 

[aldincrump]

No

 

[BridgeSmith]

Given the configuration shown in the sketch, it would seem the beam would carry torsion generated by flexure of the integral floor slab. I would surmise the stresses generated by bending of the slab exceeded the flexural capacity the masonry could sustain. Possibly, anchorage of the slab reinforcement into the masonry would not have been adequate, either.

Edit: If the slab is fully supported, it may be as suggested earlier, that it's used for aesthetic reasons, for a smooth face without joints above grade.