Deflection check
Deflection check
(OP)
Hi all. How would check the deflection of a beam supported by steel beam (which also is deflecting)? as with the attached file.
http://files.engineering.com/getfile.aspx?folder=7...
codes have different set of deflection limit but they dont say if its for global or local deflection? some say engineers who are conservative says it is global. some of the more bold ones say its is local. But what is the intention of the code regarding the deflection.
http://files.engineering.com/getfile.aspx?folder=7...
codes have different set of deflection limit but they dont say if its for global or local deflection? some say engineers who are conservative says it is global. some of the more bold ones say its is local. But what is the intention of the code regarding the deflection.






RE: Deflection check
As for considering global vs local deflections...The purpose of limiting deflection is to prevent damage to your finished surfaces and to provide a sense of comfort and security to occupants, so I think it depends on what the beams are supporting. Typically I would consider local deflections, but you have to take it case by case....if you're doing renovation work on an old structure you might get into some funky framing layouts where global deflections could make a difference. Another time where I consider globabl deflections is in formwork where you might have many layers of framing and the global deflections could be significant and noticable in the finished product.
RE: Deflection check
RE: Deflection check
RE: Deflection check
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Deflection check
RE: Deflection check
CANEIT - what i meant is that, what does the deflection criteria assume? does it assume that all supports are vertically rigid, meaning beams are supported by members with minimal vertical translation (eg. columns). Then how do we assess beams supported by beams (such as this case)? by engineering judgement?
hokie - will you compare the deflection of the cantilever to L1+L2 or just L2 only.
I dont know if you would agree, but in my own opinion it should be L1+L2, because of the settlement on the middle support
RE: Deflection check
BA
RE: Deflection check
The deflection which is important depends on the conditions of the whole structure, not just the one member. You must consider how the cantilever deflection affects the rest of the building, e.g. a facade which is carried by the cantilever and other members which may or may not deflect the same.