Two hinges arch bridge on roadway bridge 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
Two hinges arch bridge on roadway bridge へ行く。
- 1 (2013-07-20 (土) 16:00:39)

Two hinges arch bridge on roadway bridge †

1.Field of application †

Deck-type two hinges arch bridge on roadway bridge, Japan.

2.Circumstances of Repair †

Fatigue cracks were found in the intermediate vertical member ends at the arch crown connections in 1981 after 16 years of service.

↑

3.Types of structure †

The outline of the bridge structure is as follows.

Bridge length : 197.0m

Span length : 32.0m + (6.0m + 120.0m + 6.0m)+ 32.0m

Structure : Deck-type two hinges arch bridge, Gerber bridge

Deck : Reinforced concrete deck (19.0 cm thickness)

Structural steel : SS 41, SM 50, rivet SV 34, SV 41

Elevation and cross section are shown in figure 1. The number of the stiffening girders, which are spaced at 9.5m, is two. The top and bottom ends of the vertical member are bolt connected to the gusset plates which are fillet weld connected to the arch ribs and stiffening girders.

File not found: "new_pa11.gif" at page "Two hinges arch bridge on roadway bridge"[ź��]

Fig.1 Plan and elevation views.

File not found: "new_pa12.jpg" at page "Two hinges arch bridge on roadway bridge"[ź��]

Fig.2 Bearing plate support structure.

↑

4.Details of loading †

Fluctuating loads due to expressway live load.

↑

5.Description of damage †

Fatigue cracks were found in the sole plate welds at the girder supports.

Most of the cracks initiated from the weld in front of sole plate. After penetrating through the girder bottom flange, some cracks, which initiated from the welds in front of the sole plate, propagated at an angle in the girder web.

Causes of fatigue cracks were thought as follows:

Stress concentration due to the lost of the support function.

Stress concentration due to sudden change of the section.

↑

6.Repair method applied †

Emergency repair

24.5mm diameter stop holes were drilled at the crack tips and the high strength bolts of M22 were fastened there.

Permanent repair

270 by 16 by 230mm plates were installed by bolts on the girder both web sides. These plates were groove weld connected to the girder bottom flanges (Fig.3(a)).

The plates of 12mm thickness by 250mm length were installed by bolts on the bottom face of the girder bottom flange. These plates were fillet weld connected to the front side of the original sole plate (Fig.3(b)).

The effect of repair is under investigation.

File not found: "new_pa13.jpg" at page "Two hinges arch bridge on roadway bridge"[ź��]

Fig.3 Permanent repair.