ASTM A-7 grade?

[bridgeengineer2007]

Anyone know the equivalent grade of A-7 steel? 33 ksi steel seems to be the best guess but I can never understand why they didn't associate a grade with this steel back in the day.

Bridge was built in 1952....

 

[JLNJ]

Though I don't have the old complete ASTM spec, I think A7 was the grade. Tensile 60 to 72 ksi, Yield 1/2 tensile but not less than 33 ksi.

 

[PEinc]

The 1972 Manual of Structural Design and Engineering Solutions by Walmer & Baron gives the following for A-7 and A373 steels:
Yield, Fy = 33 ksi
allowable tension in net area, no voids - 20 ksi
allowable shear on web area (d x t) - 13 ksi
allowable bending on symmetrical compact section - 22 ksi +
allowable bending on unsymmetrical shapes - 20 ksi
allowable bearing on milled surfaces - 30 ksi
allowable bearing on bolts & rivets, net area - 45 ksi
welding electrode specified - E60 & E70

http://www.PeirceEngineering.com

 

[ajh1]

Most of the early ASTM standards were one grade per standard. A36 is the same way. You only need a grade designation if you want to have multiple variations listed in the same standard. Because so much of a standard is generic boilerplate language, over the years ASTM has moved to broader specs that cover a wide variety of steel grades within one standard to avoid duplication and unintentional variations within the boilerplate text.