Integrated Buildings & Structures

Assuming you are talking about residential construction,
an "upturn" beam is typically used in the ceiling of a top floor where the top of the beam extends into an attic,
and a "drop beam" is used in the ceiling over a garage or anywhere that the bottom of the beam does not extend into a usable area.
They are used when the depth of the beam required for a greater strength is actually greater than the depth of the joists around it.

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Gary W. Boyd P.E., M.ASCE
President
Boyd Engineering Inc
Magnolia TX
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A "flush" beam is one where bottom of beam is flush with bottom of joists. A "drop" beam is under the joists and ceiling.

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G Robert Fuller P.E., M.ASCE
G ROBERT FULLER, PE
Washington DC
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The primary difference (assuming a single span or condition where positive moment controls) is that upturned beams lack the lateral support, normally provided by the deck or joists, for the top (compression) portion of the beam section. 


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Manuel Morden P.E., S.E., M.ASCE
MMSE Consulting Structural Engineer
Sherman Oaks CA
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Upturn beam is as mentioned a beam where the beam depth is greater than the depth of the framing that is supporting. The compression edge/side of the beam is usually "buried" in the wall/framing above. The drop down beam supports the framing from below, for example running TJI's continuous over the top or full bearing at the end of the span. A flush beam is set flush to the top for example TJI's plane out at the top of the beam and you can run the floor sheathing continuous over the framing and the beam. There are settle differences between all three and different design methodologies that should be considered. For example,upturn beam needs to be checked for buckling in the compression edge and the attachment to it. If you are attaching to the side of the beam and below the neutral axis it will effective shear area and/or cross grain tension. I hope that helps.
Cheers,

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Allen McCoin A.M.ASCE

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