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RE: TMS 402/ASCE 4/ACI 530 Pilaster Question

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Unreinforced masonry is not permitted in high seismic zones.

 

Thanks for the reply.

 

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
 
V (949) 248-8588 F(949) 209-2509

-----Original Message-----
From: Christopher Banbury [mailto:cbanbury@ar
kengineering.net]
Sent: Tuesday, June 03, 2008 8:35 AM
To:
seaint(--nospam--at)seaint.org
Subject: RE: TMS 402/ASCE 4/ACI 530 Pilaster Question

 

The FBC has an exemption for lightly loaded columns. I don’t think that this exists in the IBC.

You might check to see if your stresses allow the use of the unreinforced masonry provisions. Even if the column is reinforced for other purposes (say beam action or axial tension) you might argue that ACI 530 2.2.2 and 3.2.1.2 permit the effect of reinforcement to be neglected for axial compression and shear.

There may also be some prescriptive methods that could be brought to bear but I don’t know of any.

 

It is unfortunate that ACI 530 lacks definitive language permitting ‘under-reinforced’ columns so-to-speak in situations where it is clearly unnecessary to provide 4 bars and/or stirrups. The work-arounds that have been described put the engineer in a compromising position unless you can get local approval of alternate means.

 

Christopher Banbury, PE

President

 

Ark Engineering, Inc.

PO Box 10129, Brooksville, FL 34603

22 North Broad ST, Brooksville, FL 34601

Phone: (352) 754-2424

Fax: (352) 754-2412

www.arkengineering.net

 

----- Original Message -----

From: Bill Allen

To: Seaint

Sent: Monday, June 02, 2008 14:46

Subject: TMS 402/ASCE 4/ACI 530 Pilaster Question

 

Are all vertical load supporting elements columns when it comes to masonry?

 

Specifically, I have a 16” square pilaster supporting a trellis. The plan checker considers this element a column and is insisting that I provide ties at 8”. I contend that the pilaster is primarily a flexural member and that fa/F’m is very, very small. I seem to recall this in the concrete section (P<=0.10f’cAg or something like that), but I don’t really see a definition of a column in the masonry section of the code. Of course, I don’t yet have TMS 402, so I’m kind of flying blind.

 

Any clarifications would be appreciated.

 

Regards,

 

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
 
V (949) 248-8588 F(949) 209-2509