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1926 - O.H. Structural Steel? 3

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justhumm

justhumm

Structural
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I'm looking at a partial bridge deck replacement in the northeastern U.S.

The existing plans for this portion of the bridge are dated 1928 and they call for the steel members to be "O.H. structural steel."

I'm not familiar with that specification. Does anyone know if it's similar or the same as ASTM A7? And does anyone know if it's weldable (for shear studs)?

Thanks!

Capture01_fhecwh.jpg


Capture02_opxomb.jpg
 
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Once again the ancient books come in handy. Good find SRE.
 
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According to a publication I have (i.e. 'Iron and Steel Beams 1873 to 1952', by AISC), from 1924 to 1931 the specifications in use are (see p.7):

ASTM A7 & A9:

55 ksi to 65 ksi (tensile strength for structural steel); min. Yield: 1/2 Tensile Strength, or not less than 30 ksi.
46 ksi to 56 ksi (tensile strength for rivet steel); min. Yield: 1/2 Tensile Strength, or not less than 25 ksi.

AISC:

"Allowable basic working stress same as 1923 (18,000 psi)."


And does anyone know if it's weldable (for shear studs)?
Click to expand...

I'm not 100% sure, but I think so. Open-Hearth steel and structural steel currently produced do have similar properties. (ASTM put out a publication comparing them some years ago.) But with steel that old, I'd be worried about what I was welding to. (I.e. is there a surface of rust?)

 
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"Ahhhh. I see," said the blind man.

Thanks!
 
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I found some more on the weldability of A7:

"Much of the steel used in buildings in the first 60 years
of the 20th century was ASTM-A7, a medium carbon steel.
This is generally accepted as being a weldable steel, but it
had a wider range of permitted carbon content than its
ASTM-A36 eventual successor. The interim ASTM-A373
steel generally is considered to have good weldability.
Although weldable with most electrodes in the E60, E70
classes, certain levels of carbon and other ingredients in
ASTM-A7 steel may require low-hydrogen electrodes and
preheating."

--'Field Welding to Existing Steel Structures', by: DAVID T. RICKER, AISC Engineering Journal. 1st quarter 1988.

The article goes on to suggest various testing techniques (to establish carbon content) and preheating temperatures for A7 & A9.
 
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""Ahhhh. I see," said the blind man." as he picked up a hammer and saw.
 
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