AISC LRFD 1.pdf

GLOSSARYxxviiLateral bracing member. A member utilized individually or as a component of a lateralbracing system to prevent buckling of members or elements and/or to resist lateralloadsLateral (or lateral-torsional) buckling. Buckling of a member involving lateral deflectionand twistLeaning column. Gravity-loaded column where connections to the frame (simple connections)do not provide resistance to lateral loadsLimit state. A condition in which a structure or component becomes unfit for service andis judged either to be no longer useful for its intended function (serviceability limitstate) or to be unsafe (strength limit state)Limit states. Limits of structural usefulness, such as brittle fracture, plastic collapse,excessive deformation, durability, fatigue, instability, and serviceabilityLoad factor. A factor that accounts for unavoidable deviations of the actual load from thenominal value and for uncertainties in the analysis that transforms the load into a loadeffectLoads. Forces or other actions that arise on structural systems from the weight of all permanentconstruction, occupants and their possessions, environmental effects, differentialsettlement, and restrained dimensional changes. Permanent loads are those loads inwhich variations in time are rare or of small magnitude. All other loads are variableloads. See Nominal loadsLRFD (Load and Resistance Factor Design). A method of proportioning structural components(members, connectors, connecting elements, and assemblages) such that noapplicable limit state is exceeded when the structure is subjected to all appropriate loadcombinationsLocal buckling. The buckling of a compression element which may precipitate the failureof the whole memberLow-cycle fatigue. Fracture resulting from a relatively high-stress range resulting in a relativelysmall number of cycles to failureLower bound load. A load computed on the basis of an assumed equilibrium moment diagramin which the moments are not greater than M p that is less than or at best equal tothe true ultimate loadMechanism. An articulated system able to deform without an increase in load, used in thespecial sense that the linkage may include real hinges or plastic hinges, or bothMechanism method. A method of plastic analysis in which equilibrium between externalforces and internal plastic hinges is calculated on the basis of an assumed mechanism.The failure load so determined is an upper boundNodal Brace. A brace that prevents the lateral movement or twist at the particular bracelocation along the length of the beam or column without any direct attachment to otherbraces at adjacent brace points. (See relative brace)Nominal loads. The magnitudes of the loads specified by the applicable codeNominal strength. The capacity of a structure or component to resist the effects of loads,LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION