Through-type Langer bridge on the roadway bridge †

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1.Field of application †

Through-type Langer bridge on the roadway bridge, Japan.

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2.Circumstances of Repair †

Fatigue cracks were found at both top and bottom ends of the vertical members.

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3.Types of structure †

This bridge is the through-type Langer bridge of which span length is 150m. The vertical members were H-type section.

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4.Details of loading †

Fluctuating loads due to wind load.

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5.Description of damage †

Fatigue cracks occurred in the changing part of the section at both top and bottom ends of the vertical members (Fig.1). The cracks propagated along the flange-web fillet welds of the vertical members and through the web plate of them. When the crack occurred, wind speed was 10 to 15 m/s.

Cause of fatigue cracks is as follows.

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6.Repair method applied †

Measure for the vibration of the vertical members was to install the device which consisted of two wire ropes and two turn buckles (Fig.2) Repair of parts subjected to cracking were performed by re-welding. Additionally, the rib plates were horizontally installed at the changing part of the section of the vertical members (Fig.3).

File not found: "Langer31.gif" at page "Steel bridge on highway I-75, Georgia, USA"[ź]

Fig.2 Measure for the vibration.


File not found: "Langer32.gif" at page "Steel bridge on highway I-75, Georgia, USA"[ź]

Fig.3 Repair method.


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