In order to make reliable estimates of bolt stresses and deformations within preloaded joints it is necessary to accuratelyrnaccount for effects of loss or uncertainty of preload, plastic deformations, sliding, prying action and possible opening ofrnjoints. These phenomena are more important for faulted loads since opening and sliding of the joint as well as plasticrndeformation may generally be permitted as long as excessive deformation or collapse is prevented. Because of therncomplexity of accounting for all of these phenomena, analysis methods are typically overly conservative for faultedrnconditions and not amenable for evaluation of joint integrity using finite element modeling.rnAlternative ways of incorporating joints in finite element models are discussed and a simple finite elementrnrepresentation of the bolt and joint interface is described. This bolt-joint model is especially applicable to bolts with neckeddownrnshanks having designs controlled by tension plus bending stresses in the shank.rnThe requirements for the joint model were that: (1) The joint representation must be simple since it was to be part of arnlarger nonlinear dynamic transient analysis model. (2) The joint representation must have load-deflection characteristics thatrnmatch expected joint efficiency factors and test load results. (3) The model should be capable of representing elasto-plasticrndeformation of the bolts and (4) Stresses and strains must be easily evaluated in individual bolts and correctly interpretedrnwith respect to faulted allowable stresses.rnThe paper includes a discussion about determination of parameters for the model and practical problems of maintainingrnnumerical stability in the dynamic solution, and evaluation of results.
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