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8/11/2019 Connections Meeting 8

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Connections Meeting

Abhishek Kulkarni

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Prediction of Fracture Initiation in Eccentrically

Loaded welded steel connections

The aim of the proposed work is to verify if the results obtained by

using the Adkins (2012) methodology on eccentrically loaded

welded steel connections reproduces adequate results.

Search experimental data.

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Research paper summary:

1) Fillet Weld Groups Loaded with Out-of-Plane Eccentricity:

Simulations and New Model for Strength Characterization

A.M. Kanvinde, ; J. Liu, ; X. Fu ; R.J. Cooke.

2) Strength of Fillet Welds as a Function of Direction of Loading

L. J. Butler ; G. L. Kulak.


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Fillet Weld Groups Loaded with Out-of-Plane Eccentricity:

Simulations and New Model for Strength Characterization A. M. Kanvinde; J. Liu; X. Fu; and R. J. Cooke. (2012)

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Reference: Fig. 1, Pg. 306. Fillet Weld Groups Loaded with Out-of-Plane Eccentricity: Simulations

and New Model for Strength CharacterizationKanvinde, A.M. et al.


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Current AISC specifications:

Strength characterization based on the work of Tide (1980)

Mean test-to-predicted ratio of 1.77 (CoV = 0.43)

Too conservative! No consideration to in plane and out of plane

eccentricities (bearing in the compression region)

Further Investigations:

Gomez et al. (2008) investigated all the existing methods for

strength characterization and inferred that Kwan et al. (2010)

Mean test-to-predicted ratio of 1.33 (CoV = 0.22)

Still on the conservative side. (considers bearing in the compressive

region)


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Development of a FE Model:

The conservative models increase the cost of welding.

A FE model is created using experimental data provided in Gomez

et al. (2008) study.

60 total tests, plate widths 44mm & 64mm also used.

Reference: Table 2, pg. 310. Fillet Weld Groups Loaded with Out-of-Plane Eccentricity: Simulations

and New Model for Strength CharacterizationKanvinde, A.M. et al.


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Challenges faced in developing the FE Model:

Weld profiles are irregular and often vary along the length.

Single pass 8mm weld has a convex profile. (throat 20% larger!)

Larger 12mm weld is close to a linear profile. (corrective effect)

For accuracy, 48 profile measurements made were then used to

create average profile.

Reference: Fig. 7, pg. 311.

Fillet Weld Groups Loaded

with Out-of-Plane Eccentricity:

Simulations and New Model

for Strength Characterization

Kanvinde, A.M. et al.


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Details of the FE Model:

Approximately 10,000 elements, with 15 elements used through the

length of the welds to characterize the stress distribution.

The irregular shape of the fillet weld profile developed using

spurious solution modes.

Elements include combinations of 20 node hexahedra and 10 nodetetrahedra.

Model incorporates large deformations & isotropic von Mises

plasticity.

Contact is modelled to consider the effect of bearing between the

plates. (Coefficient of friction is 0.8) ABAQUS 6.12


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Results & Observations:

The model is in agreement with the experimental data.

FE simulations reveal 3 interesting observations:

1) On the tension side, stress distribution is controlled by throat

yielding.2) On the compression side, welds carry a significant part of the

compressive force! (ex: 32mm plate with 13mm welds on both sides

increase the compressive width by 81.25%!)

3) On the compression side, stresses are higher than the yield strength

of the base metal. (confining effect of the surrounding material thatelevates bearing strength of the central plate.)


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FE Model:

Reference: Fig. 9, pg. 313. Fillet Weld Groups Loaded with Out-of-Plane Eccentricity: Simulations and New

Model for Strength CharacterizationKanvinde, A.M. et al.


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New improved strength characterization approach:

Reference: Fig. 11, pg.

315. Fillet Weld Groups

Loaded with Out-of-Plane

Eccentricity: Simulations

and New Model for

Strength Characterization

Kanvinde, A.M. et al.


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Study Adkins (2012) work.

Find more related work.

Next Step


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References:

1) Fillet Weld Groups Loaded with Out-of-Plane Eccentricity:

Simulations and New Model for Strength Characterization -

A. M. Kanvinde; J. Liu; X. Fu; and R. J. Cooke.

2) Strength of Fillet Welds as a Function of Direction of Loading

L. J. Butler ; G. L. Kulak.


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Comments / Suggestions?

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