ASME BTH-1:2005 pdf free download

ASME BTH-1:2005 pdf free download.Design of Below-the-Hook Lifting Devices.
1-4.3 Design Criteria
hook lilting devices shall be designed for specilied rated loads, load geometry Design category (see para. 2-2), and Service Class (see para. 2-3). Resolution of loads into forees and stress values affecting structural members, mechanical components. and connections shall be performed by an accepted analysis method.
Commentary: The original ASME 830.20 structural design requirements defined a lifting device only in terms of its rated load. Latef editions established fatigue life requirements by reference to ANSIIAWS D14.1. ASME 8TH-i now defines the design requirements of a lifter in terms of the rated load, the Design Category. and the Service Class to better match the design of the lifter to its intended service. An extended discussion of the basis of the Design Categories and Service Classes can be found in Chapters 2 and 3 Commentaries.
1-4.4 AnalysIs Methods
The allowable stresses and stress ranges defined In this Standard are based on the assumption of analysis by classical strength of material methods (models).
although other analysis methods may be used. The analysis techniques and models used by the qualified person shall accurately represent the loads, material properties, and device geometry; stress values resulting from the analysis shall be of suitable form to permit correlation with the allowable stresses defined in this Standard.
Comm.ntary: The allowable stresses defined in Chapters 3 and 4 have been developed based on the presumption that the actual stresses due to the design loads wilt be computed using classical methods Such methods effectively compute average stresses acting on a structural or mechanical element.
Consideration of the effects of stress concentrations is not normally required when determining the static strength of a lifter component (see Commentary for pap-a. 3-5.21. However, the effects of stress concentrations are most important when determining fatigue life, Lifting devices often are constructed with discontinuities or geometric stress concentrations, such as pin and bolt holes, notches, inside corners, and shaft keyways that act as initiation sites for fatigue cracks.
Analysis of a lifting device with discontinuities using linear finite element analysis will typically show peak stresses that indicate failure, where failure is defined as the point at which the applied load reaches the loss of function load (or limit state) of the part or device under consideration. This is particularly true when evaluating static strength.