The superior fire performance of heavy timbers can be attributed to the charring effect of wood. As wood members are exposed to fire, an insulating char layer is formed that protects the core of the section. Thus, beams and columns can be designed so that a sufficient cross section of wood remains to sustain the design loads for the required duration of fire exposure. A standard fire exposure is used for design purposes. Revised in January 2003 to include new tension test data, connection details, and terminology from the 2001 NDS.

The yield limit equations specified in the National Design Specification^® (NDS^®) for Wood Construction (AF&PA, 1997) for bolt, lag screw, wood screw, nail, spike and drift pin connections represent a mechanics-based approach for connection design. This approach, which was incorporated in the NDS for Wood Construction in 1991, permits the designer to determine effects of member thickness, member strength, fastener size, and fastener strength on lateral connection values for the majority of connections found in wood construction. This report covers calculation of lateral values for single dowel type fastener connections using a generalized and expanded form of the NDS yield limit equations. These general dowel equations apply to NDS connection conditions, but also permit rational and consistent treatment of gaps and fastener moment resistance, and consideration of various connection limit states. General information is provided in Part I of this report. Part II contains example problems and Part III provides equation derivations.

Lateral-torsional buckling is a limit state where beam deformation includes in-plane deformation, out-of-plane deformation and twisting. The load causing lateral instability is called the elastic lateral-torsional buckling load and is influenced by many factors such as loading and support conditions, member cross-section, and unbraced length. In the 2001 and earlier versions of the National Design Specification^® (NDS^®) for Wood Construction the limit state of lateral torsional buckling is addressed using an effective length format whereby unbraced lengths are adjusted to account for load and support conditions that influence the lateral-torsional buckling load. Another common format uses an equivalent moment factor to account for these conditions. This report describes the basis of the current effective length approach used in the NDS and summarizes the equivalent uniform moment factor approach; provides a comparison between the two approaches; and proposes modification to NDS design provisions.