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help -- allwable wind load deflection in brick veneer
i'm designing a one story commercial building with 11' high light gage steel studding as support walls. the walls are to have an exterior brick veneer attached. my question is this. what is the maximum allowable wind load deflection/length ratio for a brick veneer wall? i'm used to designing at 1/360 for typical plaster walls. i thought, however, that i once read somewhere that a maximum 1/600th of the span was allowable for brick veneer walls but i can't seem to find a reference to it. is 1/600 correct? or, can i design for 1/360 which would certainly work out better for me.
a prompt response would be greatly appreciated as i need this info right away. thanks.
paul
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i typically use l/600. us army corps of engineers literature recommends between l/600 and l/720.
mike,
i know that l/600 or 720 is a recommendation in the same plane of the brick veneer, i.e. such as a beam supporting brickwork above it, but does it also apply to deflection in a direction normal to the plane of the veneer? in this case, the deflection is in a lateral direction. does that make a difference? i've received a reply in another forum that said that the l/600 limitiation is for deflection in the plane of the brick and not normal to it, but i don't know if this is correct. do you have any info on this?
jae (visitor)17 may 00 19:35
we use l/600 for both directions.
the 97 ubc requires it for vertical deflection in 2106.2.9 and in section 1403 it is required in both directions.
the brick institute of america in 1987 issued technical note 28b which re-stated the l/600 for vertical and then recommended l/600 for the lateral also. i do not know if they have updated that tech note.
pg
my understanding of your question is as follows:
you are using a brick veneer laterally supported by a metal stud wall. this being the case ubc 1403 applies. the veneer is consider non-structural only requiring to support its own weight. any lintel in the veneer portion of the wall will have an l/600 deflection limitation. however, all other loads, including lateral loads, must be carried by the metal stud framing. your proposed lateral deflection limitation of l/360 seems very reasoable.
if the wall was being designed as a slender masonry wall then the lateral deflection is determined using a two stage load-deflection curve. the deflection of the wall when the moment is less than the cracking moment will be based on the gross moment of inertia. to obtain deflections beyond that point, the difference between actual moment and cracking moment is applied using the cracked section moment of inertia. this load-deflection behavior is based on an extensive testing program that led to the adoption of this new design method in the ubc, see chapter 21.
a deflection limitation under service lateral loads of 0.007h is applied when dealing with slender walls where the axial load is greater than 0.04f'm.
i hope that this will be of some assistance
regards
mike
i used it l/600 both directions
pg
you can refer the book 'structural masonry' by a.w.hendy(chapter on laterally loaded unreinforced walls) of macmillan publications.i think it will give you the information you are looking for.
arthurm (visitor)6 jul 00 19:41
get a copy of aci 530-99/asce 5-99. chapter 6 specifies veneer construction. it has an informative commentary.

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