PSI - Issue 64

Ayaho Miyamoto et al. / Procedia Structural Integrity 64 (2024) 464–475 Author name / Structural Integrity Procedia 00 (2019) 000–000

467

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since Dec. 2010. 35 bridges of a total 435 bridges which has 2 m or more in span length are under the jurisdiction of Ube-city located on the municipal bus routes operated by UTB. Although they account for less than 10% of all bridges in the city, after the bus monitoring system goes into service, all existing bridges in need of maintenance will be monitored with the cooperation of Ube-city Construction Department. Prior to the long-term field test using the system, short and medium span bridges to be monitored in the test were selected. The number of bridges older than 50 years as of fiscal year 2011 is 65, which is about 15% of all bridges. In 2031 (20 years later), it will increase to 323 bridges (about 74% of all bridges), indicating a rapid deterioration of the bridges in the city. Of such short and medium span bridges located on the bus routes in Ube-city, three bridges that are thought to have deteriorated considerably, namely, “Shiratsuchi Daini Bridge (two-span reinforced concrete T-girder bridge)”, “Jase Bridge (five-span prestressed concrete slab bridge)” and “Shingondai Bridge (single-span prestressed concrete girder bridge built by the Bi Prestressing Method)” were selected for the long-term monitoring in this time. Specifications and general views of these three bridges are shown in Table 1 and Fig. 2, respectively.

Table 1. Data on the bridges selected for long-term monitoring. Bridge name Completed in

Type of superstructure

Span length (m) Bridge length (m)

Start point side 1 Prestressed concrete slab bridge (pretensioned slab)

18.0 16.0 18.0 14.0 19.0

2 3 4

Prestressed concrete slab bridge (pretensioned slab) Prestressed concrete slab bridge (pretensioned slab) Prestressed concrete slab bridge (pretensioned slab)

Jase Bridge

1976 Span No.

85.0

End point side 5 Prestressed concrete slab bridge (pretensioned slab)

Shingondai Bridge Shiratsuchi Daini Bridge

1933 (estimated)

Start point side 1 End point side 2

Reinforced concrete (T-girder) Reinforced concrete (T-girder)

7.0 7.0

Span No.

15.8

June 1998

Single-span prestressed concrete girder bridge (Bi-prestressing method)

22.4

23.6

(b) Shiratsuchi Daini Bridge (two-span bridge)

(a) Shingondai Bridge (single-span bridge)

(c) Jase Bridge (five-span bridge)

Fig. 2. General views of Ube-city bus route bridges selected for long-term monitoring.