Appendix A4 HISTORICAL REVIEW OF AWS SPECIFICATIONS – 1934 TO 1999 The review of specifications through 1980 is based on notes entitled, “Welding History in AISC Manual,” by Robert F. Lorenz. Background. When the 1927 AISC Manual, 1st Ed., was published, there was virtually no mention of welding as a technique for connecting structural steel members. All references to connecting steel parts was limited to rivets or common bolts. Information on welding first appeared in 1934 and accelerated rapidly after 1945. 1934. In the 1934 AISC Manual, 2nd Ed., a single page of information reprinted extracts from an American Welding Society document. This included a cautionary note on the importance of experience both in design and process. Limiting stresses from the American Welding Society (AWS) for the throat of the weld were listed as: Shear – 11,300 psi, Tension – 13,000 psi, and Compression – 15,000 psi. Much of the welding at this time used bare wire electrodes and the lack of protecting fluxes often resulted in brittle welds. 1939. The 1939 AISC Manual, 3rd Ed., changed the limiting stress for compression from 15,000 psi to 18,000 psi. Also, a second page was added showing welding nomenclature and notation. There were still no specified rules or guidance for welding in the AISC Specification and weld details for building construction was virtually non-existent. 1941. The 1941 AISC Manual, 4th Ed., included the welding information from the previous edition, but eliminated all mention of AWS limiting stresses. Apparently the years of the Great Depression did not allow for the technical development of welding, but this was soon to change. 1946. The knowledge of arc welding obtained during World War II eliminated many of the barriers to welding acceptance. Tentative rules for welding of structural steel were established in the 1946 AISC Manual, 5th Ed. Information on welding expanded to seven pages, made up of a single page of background text, three pages of tentative standard details, two pages of AWS welded joint descriptions, and a page on welding symbols. More importantly, the 1946 AISC Specification now included guidance for welding of structural steel. Within the Specification, all references to welding pointed to AWS as a source (Section 2). Section 5 required qualification tests for operators and set criteria for welds in combination with rivets and bolts. Section 7(e) indicated that field connections were required to be made with rivets or welds. Section 9 mentioned six Electrode Classification Numbers to be specified, all in the 60 class. In section 15, Allowable Unit Stresses, compression and tension in butt welds was raised to 20,000 psi, while shear in a fillet or slot weld was limited to 13,600 psi and shear in a butt weld limited to 13,000 psi. The 50 percent increase in the tension value for butt welds (from 13,000 to 20,000 psi) opened the door for economical field welded moment connections. Sections 24 and 25 were completely devoted to welding details and limitations of geometry. Finally, in Section 33, rules of workmanship to obtain quality welded fabrication was specified. 1961-1963. The 1963 AISC Manual, 6th Ed., included the 1961 AISC Specification with changes that introduced many new opportunities for structural welding economy. Most important were the new steels. Two new carbon steels became available, A36 and A373. Both provided chemistry limits on carbon and manganese to enhance weldability. A373 was aimed at steel bridge applications, but ductility improvements in A36 eventually led to the discontinuance of A373. In addition to better weldability, the increased strength of A36 over A7 allowed for the use of E70 electrodes; this led to further economies because the shear value with E70 electrodes increased from 13,600 psi to 15,800 psi. Three new steels with higher yield points were included: A242, A440 (for riveted and bolted applications), and A441. Both A441 and A242 (certain grades) were intended for welding and low hydrogen electrodes were required.
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