Steel bridge of The Tomei Expressway のバックアップ(No.1)

バックアップ一覧
差分を表示
現在との差分を表示
ソースを表示
Steel bridge of The Tomei Expressway へ行く。
- 1 (2013-07-20 (土) 11:33:02)

Steel bridge of The Tomei Expressway †

1.Field of application †

Steel bridge of The Tomei Expressway near Hamamatsu, Japan.

2.Circumstances of Repair †

Fatigue cracks were found in the top ends of the connection plates at the transverse cross bracing locations in 1983 after 15 years of service.br;

↑

3.Types of structure †

The outline of the bridge structure is as follows.

Bridge length : three spans : (28.6 + 29.0 + 28.6 )m

four spans : (28.6 + 29.0 + 29.0 + 28.6 )m

Structure : Three spans and four spans continuous I-beam girder bridge

Deck : Reinforced concrete deck ( 19 cm thickness )

Structural steel : SM50 , SS41

Framing plan and cross section were shown in figure 1. The number of the main girders which are spaced at 2.9m is six. The floor system is composed of the floorbeams, transverse cross bracings and the lateral cross bracings . Web gap plates were weld connected between the floorbeam flanges and the girder flanges.

File not found: "Fourth6.gif" at page "Steel bridge of The Tomei Expressway"[ź��]

Fig.1 Framing plan and cross section.

↑

4.Details of loading †

Fluctuating loads due to highway live load.

↑

5.Description of damage †

Fatigue cracks were found in the welds of the web gap plates at the girder-floorbeam locations (FIg.2,3).

The characteristic of the fatigue cracks were as follows.

The frequency of the cracks (A1,A2) initiation at the top web gap plate weld are high.

The cracks which occurred at the girder web-floorbeam top flange weld were observed in the weld beads and in the weld toes of the girder both sides web.

In the bottom web gap plates, the cracks at the floorbeam bottom flanges connections were high frequency and initiated from the weld toes of the web gap plate side.

Cause of fatigue cracks was as follows:

Out-of-plane distortion resulted from the differential deflection between the girders.

File not found: "Fourth7.gif" at page "Steel bridge of The Tomei Expressway"[ź��]

Fig.2 Crack at the girder-floorbeam locations.

File not found: "Fourth8.gif" at page "Steel bridge of The Tomei Expressway"[ź��]

Fig.3 Crack around the rib (web gap) plates at the girder-floorbeam locations.

↑

6.Repair method applied †

Repair of parts subjected to cracking was performed as follows.

Replacement to the thicker web gap plates for the cracks which occurred in the girder web.

For the cracks except the above cracks, full length of the web gap plates welds to the girder top flange and the floorbeam top flange was full penetration welded and also TIG dressed (Fig.4).

File not found: "Fourth8.gif" at page "Steel bridge of The Tomei Expressway"[ź��]

Fig.4 Detail of repair.