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Kinked Beam Analysis

Kinked Beam Analysis

Kinked Beam Analysis

(OP)
I am designing a building 72 Feet Across with a reinforced concrete Ridged Roof running the entire length of the building.
The RC beams supporting the roof slab are carried on each end by bond beams over reinforced masonry walls and are kinked at the ridged peak, so from each end to the ridge is about 36 feet.
I am assuming that the base-footing connection of each CMU wall at the continuous footing is not hinged but fixed - Is this correct?
Then if the wall and beam end connections are fixed it would follow that the ridge at the peak cannot be considered hinged, but fixed also?
So there is no (or very little) movement at the peak, wall-beam connections or footing and the building is very rigid (and statically indeterminate and a stable).
In our latest project meeting review one of my colleagues suggested that the ridge and/or the footings need to be analyzed as hinges and not fixed. Is this correct?
I was also asked to consider that a cast-in-place beam 36 feet long might be an inefficient design. However this was dictated by the architect, so I'm pretty much stuck with it.
I am a civil transitioning to the structural section in our small company and just wanted your opinions as to whether my assumptions are valid.


RE: Kinked Beam Analysis

Quite likely most would assume hinged support atop the wall, for a more conservative statement of the push atop the wall. At the ridge, except some kind of hinge is built-in in construction, this is an in-situ thing and continuity (elastic fixity) should be assumed.

RE: Kinked Beam Analysis

I would like a cross section if you have one.

questions would be:

can the footing take the moment from the wall? if not then the assumption is a poor one, if the footing can take the moment, can the wall and detailing provide the moment transfer? if there is no moment at the ridge I would assume there is a lot of moment at the beam to masonry wall connection, is this capable of sustaining the moment?

the ridge can be assumed as fixed if detailed this way. you must ensure the kink is capable of carrying the moment thru detailing, I need a sketch as the zero moment sounds wrong.






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