A supplement to AWS D1.1, Structural Welding Code—Steel. Applicable to welded joints in seismic load resisting systems designed in accordance with the Seismic Provisions of the American Institute of Steel Construction, Inc. Covers additional controls on detailing, materials, workmanship, testing, and inspection necessary to achieve adequate performance of welded steel structures under conditions of severe earthquake- induced inelastic straining. Includes a commentary offering guidance on interpreting and applying this supple-ment. 124 pages, 9 annexes, commentary, 22 figures, 8 tables, (2009).