1957 steel beam strength
 

1957 steel beam strength??
i have an old building to evaluate. anyone know what was the strength of steel they used in 1957. i usually take an allowable of 20ksi, but i'm fairly close to the limit. anyone??

per aisc iron & steel beams 1873-1952 and fema 356, yield strength not less than 33 ksi. allowable tensile stress of 20 ksi.
fifth edition, manual of steel construction, 16th printing (1954)
20ksi for bending, 13 ksi for shear
fifth edition, aisc manual of steel construction, fifth printing (1948)
20 ksi bending, 13 ksi shear