Strength of Transverse Fillet Welded Joints. Analysis yields a design formula that
is more rational than the method ..... Standard for Steel Tanks, Standard Pipes,.
Strength of Transverse Fillet Welded Joints Analysis yields a design formula that is more rational than the method of treating all fillets as though loaded in the weakest direction
BY BEN KATO A N D KOJI M O R I T A
SUMMARY. The resultant force on a fillet w e l d may be transverse to t h e axis of the w e l d , inclined to the axis or parallel to the axis. The stress distribution in the w e l d and its static resistance vary materially w i t h the relative orientation of load and w e l d axis. Most of the basic investigations o n the static strength and behavior of f i l let w e l d s w e r e conducted during 1920's and 1930's (Ref. 1). It has been s h o w n that breaking loads for transversely-loaded fillets w e r e of the order of 4 0 % greater t h a n those for longitudinally-loaded fillets of the same size and length. In this paper the term transverse fillet w i l l be used to describe the former, w h i l e longitudinal fillet w i l l be used for the latter. A f e w design specifications (e.g., Ref. 2) and design methods take these differences into account, but most do not, treating all fillet w e l d s as though oriented in the weakest direction. The main reasons for neglecting the greater strength of transverse fillet w e l d s are probably an interest in simplifying design and
the fact that the performance of a transverse fillet w e l d is complex. Recently, in recognition of the remarkable improvement in quality of steel, electrode and w e l d i n g t e c h niques, extensive investigations on fillet w e l d e d joints w e r e conducted to obtain more rational design formulas (Refs. 3 , 4 ) . Regardless of w h e t h e r or not one distinguishes between the different types of fillet w e l d loads in design, it is desirable to make a study of their performance. It should aid in assessing the true effectiveness of connections proportioned by conventional methods. In this report, the static strength and behavior of transverse fillet w e l d s are studied theoretically. A n approximate solution based on the theory of elasticity is reviewed and supplemented by an elastic-plasticstrain hardening analysis performed numerically using the finite element technique. The results are compared w i t h available test results. An Approximate Approach from t h e T h e o r y of Elasticity
BEN KATO is Professor and KOJI MORITA is Assistant Professor in the Faculty of Engineering, Department of Architecture, University of Tokyo, Tokyo, Japan.
A n approximate theory on the strength of transverse fillet w e l d s w a s presented by a senior writer (Ref.
5), based on the following assumptions:: 1. The direct stress (q) on the tensile face of the w e l d is uniformly distributed (Fig. 1). 2. The pattern of the elastic stress distribution remains unchanged until the breaking of t h e w e l d . 3. Breaking w i l l occur w h e n the shear stress at a point of the fillet reaches "Cmax.= /£
nitudes are given irrespective of their orientation.a x ,
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Subroutine
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Setup Overall Matrix KT
Subroutine D£M(Calculate D* ) Subroutine DPM (Calculate D* ) •Subroutine QSRM (Calculate element stiffness matrix K e ( e m superpose K elem. o n K i )
Stiffness
4_ Setup Load Vector F. M o d i f y KT by Support I Condition
