AISC LRFD 1.pdf

xxxiiGLOSSARYUnbraced length. The distance between braced points of a member, measured betweenthe centers of gravity of the bracing membersUndercut. A notch resulting from the melting and removal of base metal at the edge of aweldUniversal-mill plate. A plate in which the longitudinal edges have been formed by a rollingprocess during manufacture. Often abbreviated as UM plateUpper bound load. A load computed on the basis of an assumed mechanism which willalways be at best equal to or greater than the true ultimate loadVertical bracing system. A system of shear walls, braced frames, or both, extendingthrough one or more floors of a buildingVon Mises yield criterion. A theory which states that inelastic action at any point in a bodyunder any combination of stresses begins only when the strain energy of distortion perunit volume absorbed at the point is equal to the strain energy of distortion absorbed perunit volume at any point in a simple tensile bar stressed to the elastic limit under a stateof uniaxial stress. It is often called the maximum strain-energy-of-distortion theory.Accordingly, shear yield occurs at 0.58 times the yield strengthWarping torsion. That portion of the total resistance to torsion that is provided by resistanceto warping of the cross sectionWeak axis. The minor principal axis of a cross sectionWeathering steel. A type of high-strength, low-alloy steel which can be used in normalenvironments (not marine) and outdoor exposures without protective paint covering.This steel develops a tight adherent rust at a decreasing rate with respect to timeWeb buckling. The buckling of a web plateWeb crippling. The local failure of a web plate in the immediate vicinity of a concentratedload or reactionWorking load. Also called service load. The actual load assumed to be acting on the structureYield moment. In a member subjected to bending, the moment at which an outer fiber firstattains the yield stressYield plateau. The portion of the stress-strain curve for uniaxial tension or compression inwhich the stress remains essentially constant during a period of substantially increasedstrainYield point. The first stress in a material at which an increase in strain occurs without anincrease in stressYield strength. The stress at which a material exhibits a specified limiting deviation fromthe proportionality of stress to strain. Deviation expressed in terms of strainYield stress. Yield point, yield strength, or yield stress level as definedYield-stress level. The average stress during yielding in the plastic range, the stress determinedin a tension test when the strain reaches 0.005 in. per in. (0.005 mm per mm)LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION