2004 Fiscal Year Final Research Report Summary
Stress Distribution and Fatigue Strength of Welded Intersection between Steel Bridge Components under multi-axial Stresses
| Project/Area Number |
15560410
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | Hosei University |
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Principal Investigator |
MORI Takeshi Hosei University, Faculty of Engineering, Professor, 工学部, 教授 (10157860)
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| Project Period (FY) |
2003 – 2004
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| Keywords | intersection between main girder and lateral girder / bi-axial stress / directional variation of principle stress / fatigue strength evaluation / 3-dimensional FEM analysis / bi-axial fatigue testing system |
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| Research Abstract |
The fatigue strength of the steel bridge component is specified on the basis of the fatigue test results under single-axial condition using model specimens for actual welded joints. However, in intersection between the main girder web and lateral girder flange, of I section plate girder bridges in which many fatigue crack experiences have been reported, bi-axial stresses occurs because the lateral girder flange stress acts by the load distribution action in addition to the main girder web stress resulting from bending of a main girder. Furthermore, in a main girder web, the direction of shear stress is reversed and the direction of the principle stress changes due to movement of load. This study is aiming at establishing fatigue strength evaluation method of the intersection between the main girder and lateral girder flange in consideration of bi-axial stress condition and the variation of principle stress.
The items performed in this research and those contents are as follows.
1.Stress
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analyses on 2 lane I section composite girder highway bridge of 30m in span (main-girder number 4) was conducted, and the stress properties at the intersection part was clarified.
2.bi-axial fatigue testing system was developed.
3.The results of fatigue test results using the bi-axial fatigue testing system were indicated for the purpose of considering the influence of two axial load on the fatigue strength of a main girder web weld.
4.The results of fatigue tests and FEM stress analysis were indicated in order to make clear of the influences of the difference in the joint form by modeling of the weld joint part on fatigue strength of lateral girder flange weld to the main girder web.
5.The results of examinations were shown on the influence of bi-axial load on the fatigue strength of a lateral girder beam flange weld.
6.The results of bi-axial fatigue tests were indicated in order to clarify influence of the direction change of the principle stress on the fatigue strength of a main girder web weld. Then it was concluded that the influence of change of the direction of the principle stress can be evaluated by the difference of the maximum principle stress and the minimum stress in a direction of maximum one at the crack originating point.
7.The fatigue strength evaluation method for the intersection between the main girder web and the lateral girder flange were proposed, and the example of fatigue examination was shown using the proposed method. Less
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