Steel Interchange

Historic Angle Shapes

I am analyzing steel roof trusses for a building constructed in 1928 with double angle webs and chords. I believe that the material was supplied from Bethlehem Steel. The top chord appears to be 2L5x3 with a thickness of either 9⁄16 or 5⁄8. Do you have any shape properties for this size angle? My manuals only go back as far as the 6th edition, and neither the AISC Iron and Steel Beams 1873 to 1952 nor AISC Design Guide 15 include properties of angle shapes.

I am also looking for information on structural steel and rivet properties for that timeframe.

Answer

Shape properties for angles have remained fairly constant over the decades, since their cross-sections do not change appreciably. I’d say just look at the section properties of the angles shown in your 6th edition Manual, but the thicknesses you mention have not been included in the AISC Manual for many decades, and were not listed in your 6th edition Manual. A close approximation can be calculated using basic engineering mechanics methods if the fillet is neglected, and we were able to send you the information from an older AISC Manual as well.

Structural steel for buildings in the 1928 timeframe generally met the ASTM A9 Standard, which had a required tensile strength of 55,000 to 65,000 psi, and a minimum yield point requirement of ½ T.S. or not less than 30,000 psi. Rivet steel had a required tensile strength of 46,000 to 56,000 psi, and a minimum yield point requirement of ½ T.S. or not less than 25,000 psi.

Kurt Gustafson, S.E., P.E.