44th UJNR Panel Meeting 2013/02/20 Gaithersburg

Outline of Japanese Design Specifications for Highway Bridges in 2012

Tetsurou KUWABARA (CAESAR,PWRI) Takashi TAMAKOSHI (NILIM)

Jun MURAKOSHI (CESAR,PWRI) Yoshitomi KIMURA (CESAR,PWRI)

Toshiaki NANAZAWA (CESAR,PWRI) Jun-ichi HOSHIKUMA (CESAR,PWRI)

1

Accumulation of the technical research achievements in terms of safety, serviceability and durability of the bridges Lessons learned from the recent earthquake, the durability

related damages of existing bridges Review of the damage estimation by the upcoming great

earthquakes such as Tokai, Tonankai, and Nankai earthquake

The 2002 Specifications Introduction of the performance-based design concept Improvement of the durability to design the sustainable bridges

Background of Revision of Japanese Design Specifications for Highway Bridge

The 2012 Specifications 2

Improvement of the requirements for easy and secure maintenance Revision of design earthquake ground motions for

interplate-type earthquake (Level 2 Type I earthquake) Introduction or improvement of specifications based on

recent research achievements • Introduction of integral abutment bridge • Improvement of minimum thickness of steel deck

plate to enhanced fatigue durability etc…

Significant Points of the 2012 Specifications

3

The Number of Road Bridges Constructed in Past Years (2011)

*Bridge length is 15m or more

Reference : Technical Note of NILIM, No.645,July 2011 4

0

30,000

60,000

90,000

120,000

150,000

180,000

0

1,000

2,000

3,000

4,000

5,000

6,000

Total N

um

ber o

f Brige

sN

um

ber of B

ridg

es

Construction Year

Others

Mix

Timber

Masonry

PC

RC

Steel

Total

50 years old or older

40 years or older

30 years or older

Damage of bearings for water leakage around end of girders

Damage of expansion joint

Fundamental Principal of Maintenance

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Background Performance of bridges has changed by applying for

various factors such as live load, seismic, environmental effects in their service period. To perceive change of bridge condition by bridge

inspection is important to sustain the bridges for a long time. Most of existing bridges are difficult to inspect because

they were designed without a view to inspecting.

Fundamental Principal of Maintenance

6

2012 Specifications Improve the requirements that structural systems which

maintenance is expected to be difficult and insecure should be avoided. Bridges should be designed in consideration of

maintenance methods such as periodic and emergency inspection, repair, retrofitted works easily and securely.

Fundamental Principal of Maintenance

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Example of providing the walkway

Fundamental Principal of Maintenance

Example of strengthening of main girder in advance for temporary jack up

8

Background The occurrence of great interplate earthquakes near Japan has been highly anticipated.

Revision of Design Earthquake Ground Motion

2012 Specifications Type I of Level 2 earthquake motion (for Interplate earthquake) was revised based on new attenuation relationships.

Zone factors for Type I earthquake motion were revised. 9

Design Earthquake Ground Motion Level 1: highly probable to occur during service period Level 2: high intensity with less probability to occur during the service period <Type I> Ground motion by large-scale interplate earthquake in the subduction area <Type II> Ground motion by near-field shallow earthquake

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Anticipated Interplate earthquake areas near Japan

Revision of Design Earthquake Ground Motion

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Zone (Zone Factor)

Revision of Design Earthquake Ground Motion

Development of new zone factor map

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Revised Design Acceleration Response Spectra Type I Type II Zone: A1

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1000

0.1 10.2 0.5 2 5

300

5000

200

500

2000

700

3

3000

Natural period (s)

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0.1 10.2 0.5 2 5

300

5000

200

500

2000

700

3

3000

Natural period (s)

(Soil Profile Type III)

Previous(2002) Revised (2012)

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Revised Design Acceleration Response Spectra Type I Type II Zone: B1 (Soil Profile Type III)

Previous(2002) Revised (2012)

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0.1 10.2 0.5 2 5

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Natural period (s)

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Design Considerations of Tsunami Effects

Superstructures inundated and washed away following failure of bearing supports

Superstructures inundated but survived

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Background Many bridges were washed away by extreme tsunami

Design Considerations of Tsunami Effects

2012 Specifications Local plan for disaster prevention shall be considered in planning of road network, structural planning and design of bridges

Recommendation For Prevention Securing of sufficient clearance for tsunami wave height For Mitigation Considerations in structural design to mitigate the tsunami-induced effect to bridges, and preparation of a recovery plan in advance

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Static loading test to examine resistant capacity of bearing supports

Simulated tsunami bore

Bridge model

Flume test for bridge model to study response of bearing supports

Experimental works to study

Response of bearing supports under tsunami-induced force through 1/20- scaled flume test

Resistant capacity of bearing supports under tsunami-induced force through 1/2-scaled static loading test

Downstream Upstream

Hydraulic Jack

Experimental Approach to Study Behavior of Bearing Supports under Tsunami-induced Force

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-20

0

20

40

60

80

100

10 15 20 25 30

p4

p5

p6

p7

p(kP

a)

t(sec)

p1 p2 p3 p4

p5 p10

p11 p12

p6 p7

p8 p9 flow

-20

0

20

40

60

80

100

10 15 20 25 30

p1

p2

p3

p(kP

a)

t(sec)

Flow pattern for 4-main girder bridge

p1-p3

p4-p7

Pressure unit converted to full scale

Observed Hydrodynamic Pressure

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Introduction of Integral Abutment Bridges Background Maintenance related problems such as corrosion at the end of girder and bearing with most of existing bridges 2012 Specifications Introduced fundamental principal of design and construction of integral abutment bridges which systems are omitted the bearing and expansion joint

(a)Portal Frame Bridge (b)Integral Abutment Bridge

Superstructure

Abutment

Pile Foundation

Superstructure

Abutment

Single row Pile Foundation

Omitted Expansion joint Bearing

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Damage of Pavement on the Crack

Improvement of Fatigue Durability of Steel Deck

Background Fatigue cracks to penetrate a deck in a weld of closed rib and deck plate have been increased in the existing steel slabs. 2012 Specifications Minimum thickness of deck plate where wheel load of heavy vehicle is always loaded is prescribed more than 16mm (previous: 12mm) in case of steel deck using closed rib.

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デッキプレート

Ｕリブ

デッキプレート

Uリブ

溶接ビード

亀裂

亀裂

ルート部ルート部※

デッキプレートの板曲げ変形

Closed rib

Crack

Deck plate

Crack Deck plate

Closed rib

Root Weld bead Root

Bending deformation of deck plate

Summaries

The 2012 Design Specifications for Highway Bridges were revised about mainly;

• Designing the bridge with consideration of the maintenance and redundancy

• Revision of design ground motions for interplate-type earthquake

• Introduction or improvement of specifications based on recent research results

We continue to examine to introduce the load and

resistance factor design concept for next revision. T/C G initiates collaborative research program on tsunami

effects on bridge performance. 20

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Thank you for your kind attention

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Natural period (s)

Soil profile type

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0.1 10.2 0.5 2 5

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Natural period (s)

Standard Acceleration Response Spectra (Type I earthquake)

Previous(2002) Revised (2012)

Type II Type I Type III