Distribution of Stress Concentration Factors along the Weld Toe of Tubular KT-joints in Truss Bridges

Subject Areas : Analysis of Structure and Earthquake

rasol Bageri ¹ , mohammadali lotfolahiyagin ² , Hamid Ahmadi ³

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Received: 2010-08-31 Accepted : 2010-12-30 Published : 2010-12-22

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Abstract :

Many research works have been accomplished so far on the computation of stress concentration factors (SCFs) for various types of tubular joints. Almost all these studies have focused on values of the SCF at the saddle and crown positions, and they have ignored the HSS at other locations along weld toe. However, SCF distribution is very important for predicting the fatigue crack growth, determining the fatigue life of intact joints and estimating the remaining life for in-service cracked joints. In this paper, the effect of normalized geometrical parameters (τ, γ, β and ζ) and the brace-to-chord inclination angle (θ) on the distribution of stress concentration factors (SCFs) along the weld toe of tubular KT-joints under the balanced axial loads is studied. The results of the parametric study showed that both the distribution of SCFs along the weld toe and the location of HSS are dependent on the values of geometrical parameters. Hence, the HSS may not be always located at either saddle or crown lacation. It was also concluded in the global scale that the increase of τ and/or γ results in the increase of SCFs in all positions along the weld toe, and the increase of β leads to decrease of SCFs in saddle and crown heel locations. The reason may be the increase of the stiffness of the joint due to the increase of β. The change of ζ has generally no considerable effect on both the values and distribution pattern of SCFs along the weld toe, and the increase of  θ leads to the increase of SCFs in all positions along the brace-chord intersection.