Effective Notch Stress Method for Fatigue Evaluation of Welded Joints in a Steel Bridge Deck

The existing S-N curves by effective notch stress to assess the fatigue life of gusset welded joints can result in reduced accuracy due to the oversimplification of bead geometries. The present work proposes the parametric formulae of stress concentration factor (SCF) for as-welded gusset joints based on the spline model, by which the effective notch stress can be accurately calculated for fatigue resistance assessment. The spline model is also modified to make it applicable to the additional weld. The fatigue resistance of as-welded and additional-welded specimens is assessed considering the geometric effects and weld profiles. The results show that the error of SCFs by the proposed formulae is proven to be smaller than 5%. The additional weld can increase the fatigue life by as great as 9.4 times, mainly because the increasing weld toe radius and weld leg length lead to the smaller SCF. The proposed series of S-N curves, considering different SCFs, can be used to assess the welded joints with various geometric parameters and weld profiles.

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Effective-notch-stress-based fatigue evaluation of rib-deck welds integrating the full-range S—N curve concept

Journal of Constructional Steel Research ◽

10.1016/j.jcsr.2021.106541 ◽

2021 ◽

Vol 179 ◽

pp. 106541

Author(s):

Qiudong Wang ◽

Bohai Ji ◽

Tian Gao ◽

Zhongqiu Fu

Keyword(s):

Full Range ◽

Notch Stress ◽

Effective Notch Stress ◽

Fatigue Evaluation

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APPLICABILITY OF EFFECTIVE NOTCH STRESS CONCEPTION TO FATIGUE STRENGTH EVALUATION FOR CRUCIFORM WELDED JOINTS FAILING FROM WELD ROOT

Doboku Gakkai Ronbunshuu A ◽

10.2208/jsceja.65.188 ◽

2009 ◽

Vol 65 (1) ◽

pp. 188-195 ◽

Cited By ~ 2

Author(s):

Takeshi MORI ◽

Masao MYOKEN

Keyword(s):

Fatigue Strength ◽

Welded Joints ◽

Strength Evaluation ◽

Notch Stress ◽

Effective Notch Stress ◽

Weld Root

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Influence of backing materials towards the fatigue strength of butt-welded joints

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406211403570 ◽

2011 ◽

Vol 225 (8) ◽

pp. 1798-1807 ◽

Cited By ~ 3

Author(s):

M H Kim ◽

H J Kim ◽

J H Han ◽

J M Lee ◽

Y D Kim ◽

...

Keyword(s):

Finite Element ◽

Fatigue Strength ◽

Welded Joints ◽

Fatigue Tests ◽

Experimental Results ◽

Finite Element Analyses ◽

Cold Metal Transfer ◽

Notch Stress ◽

Effective Notch Stress ◽

Cold Metal

The purpose of this study is to investigate the fatigue strength of butt-welded joints with special attention paid to employing different kinds of backing plates. The effect of the under-matched weld was also considered. Four different cases of backing scenarios for butt-welded specimens such as steel backing, ceramic backing, CMT (no backing by cold metal transfer) and UM (under-matched welded specimen) were investigated. A series of fatigue tests was performed to compare the fatigue strength of butt-welded joints with respect to different backing scenarios. Effective notch stress was used for the interpretation of fatigue strength of butt-welded specimens with backing plates based on finite element analyses for calculating fatigue notch factors. When results were presented from the effective notch stress, all backing scenarios considered in this study exhibited the fatigue strengths corresponding to the FAT 225 curve. From the experimental results of this study, it was determined that the fatigue strengths of butt-welded joints were found to be in the order of CMT, ceramic backing, UM, and steel backing. No significant decrease in fatigue strength, however, was observed when backing plates were steel backing and ceramic backing types.

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Modeling of Welding Joint Using Effective Notch Stress Approach for Misalignment Analysis

Volume 9: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2015-51717 ◽

2015 ◽

Author(s):

Md Nuruzzaman ◽

Christine Q. Wu ◽

Olanrewaju Ojo

Keyword(s):

Stress Distribution ◽

Welded Joints ◽

Experimental Validation ◽

Structural Integrity ◽

Parameter Tuning ◽

Joint Modeling ◽

Tuning Parameter ◽

Notch Radius ◽

Notch Stress ◽

Effective Notch Stress

This research represents the methodology to develop a weld model to assess the structural integrity of welded joints based on stress analysis by finite element method (FEM) and experimental validation. The stress distribution in the welded joints mainly depends on geometry, loading type and material properties. So, it is a great challenge to develop a weld model to predict the behavior of stress distribution and weld stiffness in the joints. In this study, the effective notch stress approach has been used for weld joint modeling. Parameter tuning has been done for the lowest experimental validation error. The effective notch radius is the only tuning parameter in this weld model. The weld model with effective notch radius in between 0.1 to 0.2 mm has shown a good agreement with the experimental results. Through this study, the weld model based on effect notch stress has been validated experimentally for the first time. The validated weld model was then used for misalignment analysis. Both experimental and FE results confirmed that axial misalignment of 20% of specimen’s thickness would have increased maximum principle stresses more than 25–30%.

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