Required Number of Anchors & Mechanical Anchoring 1

[Deutero]

I recall approximately ten years ago, when a PEMB company (specifically ABC) had changed their rigid frame base plate anchoring from two anchor bolts to four anchor bolts. Apparently for some time, the two were acceptable. I do not recall whether the change was a code requirement or revised company standard. Likewise, I don't know if a minimum of four anchors is a requirement for any structural columnar framing.

I often need to design hot-rolled lintels supported by HSS columns that are within existing wood or CFS walls, to bear on existing concrete stem walls. Obviously, CIP anchors are out.

The edge distance and spacing requirements of mechanical and adhesive anchors make this a difficult and sometimes a seemingly impossible task, IF, four anchors are required. Even if only two anchors would be requried, it can be extremely difficult and tedious to comply with all the fastener manufacturer requirements when a significant amount of uplift is concerned.

If there is a code requirement for four anchors regarding specific structural members, please show me where. If not a requirement, I want opinions.

If the lintel/header is fastened/tied to the wall in an acceptable manner as per the EOR, why would I need to specify four base plate anchors? The walls themselves are only fastened at 32" oc. Granted, as the rigid frames are laterally tied to each other, the wood or CFS walls are typically tied to cross walls and/or a floor or roof structure. But, if the lintel is also sufficiently tied as deemed by EOR, to the wall, which is concurrently tied to the other, can two anchors suffice?

What are your thoughts? Thank you ...

 

[swearingen]

It is an OSHA requirement designed to help ensure steel erector safety. The link below gives the section involved. Be sure to click on the section designation and read through the three clarification letters to get a better understanding on why this requirement exists.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=12746

 

[DaveAtkins]

OSHA allows two bolt base plates at "posts", which are defined as vertical members which are EITHER not vertically loaded but are restrained by the member above (e.g., wind columns) OR are vertically loaded but weigh less than 300 lbs (i.e., the column itself weighs less than 300 lbs).

With this exception, I almost never use four bolt base plates at exterior columns in single story buildings.

DaveAtkins

 

[Deutero]

DaveAtkins,

Where do you find this exception?

 

[DaveAtkins]

I don't have the OSHA standard, but this exeception was mentioned in the November 2001 issue of Structure magazine.

DaveAtkins