M Bridge のバックアップ(No.3) - PukiWiki

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差分を表示
現在との差分を表示
ソースを表示
M Bridge へ行く。
- 1 (2014-04-04 (金) 13:34:32)
- 2 (2014-04-04 (金) 16:32:18)
- 3 (2014-08-18 (月) 15:20:54)

M Bridge †

M橋 †

1.Field of application †

M Bridge in Tokyo, Japan.

M橋（東京都）

2.Circumstances of Repair †

The fatigue crack ,that length was 245mm, was found at the web panel of the end of the girder in the A2 support.

A2支点側の主桁端部WEBに長さ245mmに疲労き裂が見つかった。

3.Types of structure †

The outline of the bridge structure is as follows.

橋梁の構造諸元は次のとおりである。

Bridge length : 250.0 m
Span length : 43.0m + 52.0m + 60.0m + 52.0m + 43.0m
Structure : Five spans continuous box girder bridge with orthotropic deck system
Structural steel : SM41

橋長：250.0m
支間長：43+52+60+52+43m
橋梁形式：5径間連続鋼床版箱桁橋
使用鋼材：SM41

Elevation,plan and cross section of M bridge is shown in Fig.1.

一般図を図.1に示す。

Fig.1 Elevation,plan and cross section of M bridge.

図.1 M橋の一般図.

4.Details of loading †

Fluctuating loads due to vehicles live load.

活荷重

5.Description of damage †

The location and the detail of the crack are shown in Fig.2.Fig.3 shows the part which was surrounded in the lower flange,the end of diaphragm and the horizontal stiffener.This part corroded remarkably.The stagnant water was thought as the cause of the localized corrosion like this.As a result of having measured a residual thickness with a ultrasonic thickness gauge, it was revealed that the thinnest part was 1.8mm.

図.2に疲労き裂の位置と詳細を示す。図.3は下フランジ、端ダイヤフラムおよび水平補剛材で囲まれた部分を示すが、この部分はかなりさびが進行していた。滞水が局所的さびの原因であると考えられた。残存板厚を超音波板厚計で測定した結果、もっとも薄い部分で、1.8mmであった。

Fig.2 Location and detail of crack.

Fig.3 Corrosion in the box girder.

Causes of the fatigue crack were thought as follows:

Fatigue due to repeated high support reaction.

Repeated out-of-plane deformation of the web plate at the welded joints of the web plate and the lower flange.

6.Repair method applied †

Bolted splice plates were installed(Fig.4,Fig.5).

Fig.4 Detail of the repair.

Fig.5 Photograph of the repair((a):The part of support.(b):Outer surface of the girder.(c):Inner surface of the girder.)

Reference †

Chitoshi Miki,Fatigue and destruction of bridge,2011.10(In Japanese)