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RE: Bar Joists - What do the letters actually mean ?

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I obtained a brief history from the SMI Joist Catalog.  These dates may not be
absolutely exact.  SMI manufactures out of Hope, AR.

1928: SJI founded.  Joists covered by standards were later called SJ-Series
1953: Longspan Steel Joists (L-series) introduced.  Up to 96 ft long, 48 in
deep.
1959: S-Series joists replace SJ-Series.  Allowable stress increased to 20,000
psi from 18,000 psi.
1961: J-Series replace S-Series.  Allowable stress increase from 20,000 psi to
22,000 psi.  LA-Series replace L-Series (same reason).  H-series introduced
with 50,000 psi yield chords.
1962: Introduce LH Series joists with 50,000 psi yield.
1965: One spec for H and J joists.
1966: LJ-Series replaces LA-Series.  Single spec for LJ and LH.
1970: Introduce DLJ and DLH-Series.  Up to 144 ft span, 72 in depth.
1971: Eliminate no. 2 chord size and add 8" deep J and H-joists.
1972: Consolodation and expansion of spec's.
1978: Eliminate J, LJ, and DLJ in preference of 50 ksi material.
1986: Introduction of K-Series for several reasons.
 1. Better economy from new design concept.
 2. Meet demand for lighter roofs
 3. Create joists that match usual load configurations
 4. Eliminate over-weight joists rarely ordered or used.
1994: Introduce KCS "Constant Shear" joists.

hope that helps.

Keith Fix, PE
Cromwell Architects Engineers
--- desi.kiss(--nospam--at)theaustin.com wrote:
> 
> RE: H, K, J series joists.
> 
> Todd Hill wrote:
> What do the letters actually mean ?
> 
> The letters actually don't mean anything !!!!!!!!!!!!!
> 
> They could be replaced by :
> 
>    yellow, pink, or red
>    X, Y,Z
>    @,#,% etc.
> 
> 
> Since 1920 the letters changed constantly !!!!!!!!!
> 
> Hope this helps.
> 
> Desi J. Kiss
> 
> 
> 


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