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1 008 stress behavior at the joint of stringer to cross beam of the steel railway bridge

2 1..FEM FEM 3. 4.

4 ABSTRACT 1. BackgroundPurpose The occurrence of fatigue crack is reported in the joint of stringer to cross beam in the plate girder bridge.the crack occurs from rivet of connection plate where stringer ties to cross beam, the coped detail of the stringer web of lower flange side, and the upper flange. This research pays attention to the crack from the coped detail of the web among these cracks. In this research, the stress behavior at the coped detail is examined, aiming to give useful dates for repair and reinforcement, and for a new design to reduce the stress at the web coped detail. The cause of the stress concentration of the cracking part is investigated by comparing with the truss bridge in which the cracking is not reported.. FEM analysis In this research, the bridge was modeled, and the influence line of the cracking part was examined by using the FEM analysis. On truss bridges, there are two types of cross beams. One type, the diagonal members are jointed to the lower chord member, and another type, to the upper chord member. The stress behavior at the coped detail varies depending on the cross beam position. The former behaves as the continuous beam and the influence line of the latter is biased to the tension side. The variation of the stress properties of coped detail with cross beam position was small because the structure of the joint of cross beam to the main girder of the plate girder bridge was uniform, and in-plane stress component of tension appears. 3. Train running simulationstress range histogram The numerical simulation was conducted to aim to get a stress history at the coped detail with the train passage by using these influence lines. The stress histories of the plate girder bridge show the very high tension. On truss bridge, stress history of the cross beams that have a diagonal on the lower chord member is biased to compression side, but stress history of cross beams that have a diagonal on the upper chord member shows the high stress of tension. Stress range histogram was made by using rain flow method to evaluate the simulation result from the viewpoint of fatigue. From the stress range and the frequency the plate girder bridge was severer from the view point of fatigue comparing with the truss bridge. 4. Influence of cross beam The cause of the difference in stress behavior of the plate girder bridge and the truss bridge was investigated. Comparing the detail of each bridge, it was found that the ratio of the

This research pays attention to the crack from the coped detail of the web among these cracks.

5 height of the cross beam to the span is remarkably different. Therefore, considering that the bending of cross beam may affect stress behavior of each bridge, the models were analyzed, in which the section of cross beams are varied. As a result, the section of the cross beam was found to influence the stress behavior greatly. The cause of difference of stress behavior was examined on the two types of cross beam of the truss bridge. It is supposed that the constrait to the cross beam by the main truss may vary depending on the cross beam types. Therefore, the rotation and the torsional deformation of the cross beam are examined from both displacements of the cross beam at the join to the stringer and to the main truss. As a result, the rotation of cross beams at the join to the truss that has a diagonal on the side of lower chord member is smaller than the cross beam that has a diagonal on the side of upper chord member and the cross beam is suffered from the torsional deformation. An additional analysis, to confirm the effect of the rotation and the torsion of cross beam was conducted. However, the expected result cannot be obtained.

As a result, the section of the cross beam was found to influence the stress behavior greatly.

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The Evaluation of LBB Behavior and Crack Opening Displacement on Statically Indeterminate Piping System Subjected to Monotonic Load The plastic collap

The Evaluation of LBB Behavior and Crack Opening Displacement on Statically Indeterminate Piping System Subjected to Monotonic Load The plastic collapse and LBB behavior of statically indeterminate piping