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RE: brick veneer support deflection

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In addition, section 5.6.1 of the ACI 530-95 (also cross-reference as ASCE
5-95/TMS 402-95) Masonry Code or section 1.10.1 of the ACI 530-99 Masonry
code deals with "deflection of beam and lintels".  This section states that:

Deflection of beams and lintels due to dead plus live loads shall not
exceed l/600 nor 0.3 in. (7.6 mm) when providing vertical support to
masonry elements designed in accordance with Chapter 6 or Chapter 9.

Note: This exact wording is taken from ACI 530-95.  Chapter 6 is design of
unreinforced masonry using the "engineered" approach and Chapter 9 is
empirical design.

If my memory serves me correctly, this criteria is to minimize/prevent
cracking in masonry walls that are not supported on grade (either slabs on
grade or foundation walls).

Hope this helps.

Scott

------------------------------------------
Scott E. Maxwell, PE
Structural Engineer

SmithGroup Inc.
500 Griswold, Suite 500
Detroit, MI  48226

Phone: (313) 442-8253
Fax:   (313) 442-8297

Work Email:     smaxwell(--nospam--at)dt.smithgroup.com
Personal Email: smaxwell(--nospam--at)engin.umich.edu
------------------------------------------

 At 08:34 PM 01/24/2000 -0500, you wrote:
>Also: This is very strict, especially the 0.3" in one case this would be
>L/1100. Would it make sense to use shear studs on the perimeter beams to
>increase stiffness??? I would likely use a lesser amount for lateral
>support reasons anyway. I don't use shear studs too often; would the
>increase in stiffness be considerable or marginal?
>thanks again, David Handy
>
>At 06:36 PM 1/24/00 -0600, you wrote:
>>David,
>>
>>The UBC says to use L/600 for total deflection.  The BIA says the lessor of
>>L/600 or 0.3".  I tend to agree with the BIA unless you can cut the masonry
>>into smaller panels with properly detailed joints that can accommodate more
>>movement.  I would recommend that you read the BIA Technical Note 28B.
>>
>>Regards,
>>Harold Sprague
>>
>>> -----Original Message-----
>>> From:	David Handy [SMTP:dhandy(--nospam--at)trg.ca]
>>> Sent:	Monday, January 24, 2000 6:15 PM
>>> To:	seaint(--nospam--at)seaint.org
>>> Subject:	brick veneer support deflection
>>> 
>>> What values do you use for meeting deflection requirements when supporting
>>> brick veneer at every floor. For example I have a building that use cast
>>> in
>>> lintel angle wedge inserts. There is a 3" concrete slab for the floors
>>> that
>>> is composite with the joists (HAMBRO). At the perimeter I am planning on a
>>> steel beam with the slab thickened to 8" to provide enough concrete for
>>> the
>>> anchors. This beam supports only a small strip of floor where parallel to
>>> the joists and supports a 10' trib of floor where perpendicular. The shelf
>>> angle at the edge of the slab supports about 12' of brick at each floor.
>>> 
>>> I have typically used L/720 for the beams using the live load plus half of
>>> the weight of the brick wall as the means for evaluating the deflection. I
>>> know that many would use just the live load and maybe even a less strict
>>> L/???. What do you think?
>>> 
>>> David Handy, P.Eng
>>> Ontario, Canada
>
>
>