International Institute of Welding

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Repair of fatigue loaded welded structures

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CAUSES AND REPAIRING METHODS OF FATIGUE DAMAGED BRIDGES

The causes of fatigue of steel bridge may be classified as follows.
  1. Welding defects were included at the time of fabrication.
  2. An inappropriate structural detail of low fatigue strength had been adopted.
  3. Stresses and deformations unforeseen in design occurred at joints of members.
  4. The structure behaved in a manner not expected such as due to vibration.

There are two approaches to repairing and retrofitting, removal of the cause of damage or to alleviate it and increasing the fatigue strength of the detail. The concrete measures are as follows.

  1. removal of crack
  2. re-weld
  3. surface treatments such as TIG dressing and Peening.
  4. re-weld + post weld surface treatments
  5. bolted splice
  6. shape improving
  7. stop hole
  8. modification of connection detail

Applicability of these methods is shown in the following table.

 

A

B

C

D

E

F

G

H

1

G

G

  

G

E

G

  

G

2

F

F

G

E

E

E

G

E

3

F

F

G

G

E

G

G

E

4

F

F

G

G

E

G

G

E
E: Excellent G: Good F: Fair N: No good
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Document Download :

Retrofitting Engineering for Steel Bridge Structures (Rev.1) Doc. XIII WG5-74-07 July 2007 (214pages, 15MB)

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Last update: 2006/07/20.