findings and proposals/recommendations

1

For Resilient Infrastructures Development in Nepal

Findings and Proposals/Recommendations

1. Sustainable Infrastructures and Key Recommendation

2. Vulnerability Study for Roads & Bridges in Kathmandu Metropolitan Area

3. Development of Nepal Own Seismic Design Code 4. Improvement of Roads in Rural/Mountain Areas

Shigeki UNJOH, Dr. Eng., PE PWRI, MLIT, JAPAN

MLIT Support Team

2

For Sustainable Infrastructures

Sustainability of Infrastructures -Roads and Bridges-

Planning and Structural

Design Necessary

Requirement and Function

Seismic Design

Construction Quality Control

Materials Construction Technology

Maintenance Operation Inspection

(Ordinary, Emergency)

Rating Repair Works

Seismic Retrofit

Issues for Consistency 1. Policies and Codes Development

2. Technology Development/Accumulation and Dissemination/Education System of Engineers

(Government, Academia, and related Organizations)

MLIT Support Team

Engineering

Association

Construction

Companies

3

Key Recommendation: Establishment of Technology Development Group/Committee/ Organization in Nepal (For Ex. Bridges)

Gov. of Nepal

MOPIT

DOR

Supporting and Advising International Community

MLIT Support Team

MOFALD

DOLIAAR

NPC

MOUD

KVDA

MOI

DWIDP

///////

Academia Government

Consulting

Firms

Bridge

Makers

Bearing

Makers

Technology Development

Committee

-Bridge Committee- Theory and Real Practice

New Technology, Information

Sharing, Education,

Code Development and

Dissemination

(Design, Construction,

Maintenance)

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2. Vulnerability Study for Roads & Bridges in Kathmandu Metropolitan Area

MLIT Support Team

Objectives of Vulnerability Study for Road and Bridges in Kathmandu Proposal of Urban Recovery Planning in Kathmandu

Metropolitan Area based on BBB Concept

Long-term comprehensive urban recovery planning in Kathmandu metropolitan area, based on the future population forecast, future urban structure, land use plan, transportation plan, risk assessment, etc.

Vulnerability Study for Roads and Bridges

As a basis for Urban Recovery Planning in Kathmandu

To Prepare Next Possible Earthquakes in Future

Next Earthquake M8 class EQ near in Kathamndu

Damage to be prevented and Expected Performance

No Collapse, No Unseating, and Quick Recovery of Road Function

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MLIT Support Team

Damage to Bridge

Lifeline:

Water Pipes

Weak and Non-

ductile Stopper

MLIT Support Team

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Simplified Evaluation Method for Seismic Performance

Vulnerability Study of Bridges

Start

Superstructure Substructure

(Pier and Abutment)

Unseating

1)Bearing Supports

(Stiff/Weak)

2) Stopper (Stiff/Weak)

3) Support Length

(Small/Long)

Foundation

1) Material (Brick/Wood/RC)

2) Stiff/Soft (Liquefaction/Soft Soil)

3) Scour (Serious/Light)

Column

1) Material (Brick/Wood/RC)

2) Type of

Section (Wall/Single)

3) Shear Failure

Abutment

1) Material (Brick/Wood/

RC)

Vulnerability Ranking on Possibility of Serious Damage (Tentative) Rank A: High Possibility Rank B: Medium Possibility Rank C: Low Possibility

Key Issues: Hazard/Importance/Vulnerability Vulnerability: Design Standard Applied is also essential issue.

MLIT Support Team

Design Drawings, Current Condition

Data, Soil Condition, etc.

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Yearly Construction of Bridges Total Road Length = 12,500km (approx) Number of bridges（1,709 bridges, data available for 558 bridges） 3 Year Program: 400 Bridge Constructions (Road: 3,000km)

Analysis of Current Status of Roads and Bridges

Weak Shear

Strength and Low

Ductility Design After Kobe

MLIT Support Team

Data of 558/1709

*) The data is from Web-based Nepal ‘Bridge Management System.’

1995 Kobe EQ 2011 Great East Japan EQ

Research Projects Experimental Researches for Seismic Retrofit

1982 Urakawa-oki EQ

Seismic Retrofit Improved Seismic Performance

Retrofit

LESSONS

･Increase of Design Acceleration ･ Improvement of Ductility

Code Revision

Damage

Unretrofitted Bridges Repeated Similar

Damage Observed in Past EQs

Retrofitted Bridges Suffered Minor

Damage except a Few Bridges 9

MLIT Support Team

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Seismic Retrofit Program in US for Older Bridges

By Caltrans (refer to http://www.dot.ca.gov/hq/paffairs/about/retrofit.htm)

MLIT Support Team

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Provision of Current Condition Data for Bridges

MLIT Support Team

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Simplified Evaluation Method #1 (Materials)


Start

Material

Masonry, Wood (Unstable)

Rank A

Spans Rank C

Single span + Abutment RC, Steel (Stable)

Multi span + Pier

Check

Superstructure

And

Substructure

Rank A: Detailed Study

including

Capacity/Demand Ratio

Analysis including

Construction Condition

of Masonry.

MLIT Support Team

13

Simplified Evaluation Method #2 (Support Length)


Start

Superstructure

Unseating Prevention

Support Length

SE<40cm: Rank A

70cm>SE>40cm: Rank B (AASHTO Code)

SE>70cm: Rank C (JRA Code)

If the following devices are provided,

1) Bearing Supports

Design Force >IRC Code: Stiff, or

2) Additional Stopper

Design Force > IRC Code: Stiff

Rank B to Rank C

Rank A to Rank B


including


Analysis

Installation of Stoppers

or Widening of Seat

Width

MLIT Support Team

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Simplified Evaluation Method #3 (Shear of Column)


Start

Substructure

(Column)

Section Type Wall (b/a>3)

Rank B Single(b/a<3) or Multi Column (Circular)

Possible

Shear Failure

Shear Failure

(h/D<3)

Bending

Failure (h/D>3)

Shear Re-bar

Poor

Rank A

Rank B

Good

Confinement

Re-bar

Rank C

Rank B

Good

Poor


including


Analysis

Steel/Fiber/RC Jacketing

Of Columns

Width(TR): b

Width(LG): a

Height: h

Width: D

MLIT Support Team

*) If TR direction of multi-columns

is considered, h shall be h/2

because of bending moment.

*) This is a case for columns without

design information including

drawings. If there is, the check can

be made based on them.

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Simplified Evaluation Method #4 (Foundation Stability)


Start

Substructure(Foundation)

Topographical

Classification

1. Current/Previous River Area,

Reclaimed area, Embankment

on Water Area, Low Ground

Area between Sand Hills

Rank C Check Scour

Effect

Not Significant

Rank A

Significant


including FL/PL Values

and Thickness of

Liquefiable Layers

Rank C

Low Ground Area

other than 1.

Highland, Hill,

Mountain Area

Rank B

Rank A

Check Soil Type

and Underground

Water Level Saturated Sandy Soil

Layer, No Information

Others

MLIT Support Team

Emergency Transport Routes: Bridges on Ring Road and Arniko Highway

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1

2

3

6

7

8

9

29

5

10

Kathmandu

28

1’

30

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Vulnerability Ranking on Possibility of Serious Damage (Tentative, need Detailed Study) A: High Possibility B: Medium Possibility C: Low Possibility *)Check Points 1)Connection of Girder (Stiff or Weak) 2)Seat Width (Small or Large) 3)Columns (Shear Failure, Need Check Re-bar Arrangement) 4)Foundations (Stiff or Soft, Scour) 5)Others (Deterioration)

MLIT Support Team

4

c OpenStreetMap contributors

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12

13

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25

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17

16

19

20

24

23

11

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Vulnerability Ranking on Possibility of Serious Damage (Tentative, need Detailed Study) A: High Possibility B: Medium Possibility C: Low Possibility *)Check Points 1)Connection of Girder (Stiff or Weak) 2)Seat Width (Small or Large) 3)Columns (Shear Failure, Need Check Re-bar Arrangement) 4)Foundations (Stiff or Soft, Scour) 5)Others (Deterioration)

MLIT Support Team Emergency Transport Routes: Bridges inside Ring Road


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Bridge #1 (Rank A, Deterioration) MLIT Support Team

Bridge #7 (Rank A)

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MLIT Support Team

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Simplified Evaluation Method for Deterioration


Start

Superstructure Substructure

(Pier and Abutment)

Girder Slab Bearing Ex. Joint Foundation

(Scour) Column Abutment

Deterioration Evaluation (Tentative) Rank A: Need Urgent Treatment (Unsafe Situation) (Need Detailed Study) Rank B: Need Repair and Replacement in early time Rank C: Continuous Monitoring Rank D: Fair Standardized Evaluation Method of Rank A to D (Photos and Sketches)

MLIT Support Team

Deterioration (1) Slab and Joints

Rank A: Joint and Slab

Handrail

Pedestrian Deck

MLIT Support Team

21

Deterioration (2): Scour of Foundation

22

Bridge closed with

large Inclination

caused by

Scouring Effect

Rank A: Scour

Rank A: Scour

Rank B:

Backfill Soil

(Settlement)

MLIT Support Team

Vulnerability Study of Pedestrian Bridges

1 2

3

4

6

7

8

9

11

5

10

Kathmandu

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Vulnerability Ranking on Possibility of Serious Damage (Tentative, need Detailed Study) A: High Possibility B: Medium Possibility C: Low Possibility *)Check Points 1)Connection of Girder (Stiff or Weak) 2)Seat Width (Small or Large) 3)Columns (Need Check Re-bar Arrangement (Shear)) 4)Others (Deterioration)

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1４

MLIT Support Team


Damage to Pedestrian Bridge

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No Offset

Tilted Column Tilted Column

Residual Displacement at Bearing: 46cm

MLIT Support Team

Vulnerable Pedestrian Bridges

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Damaged Bridge

Rank A: Skewed Girder Rank A: Column:

Need to Check Re-bar

Ar.

Rank A: Seat Width

MLIT Support Team

Damage to Earth Structures: Soft Soil, Sliding, Settlement, Drainage (Need Detailed Study)

26

MLIT Support Team

Large Slide and Cracks:

Need Detailed Study of

Soil Foundation

Embankment Section New Cracks in Retaining Wall (Need Detailed Study)

MLIT Support Team

27

Water Drainage is

not enough.


Road Function and Bottleneck Issues: Bridge Width and Footways

MLIT Support Team

28

Bottlenecked Section of Width

Narrow Width and No Footway

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Structures to Reduce River Section Significantly

MLIT Support Team

Japanese Practice: Bridge Design Plan minimizing the Effect on River Flooding

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50m or more Less than 50m

Specified Rules for Location of Bridge Abutment

MLIT Support Team

Minimizing the effect on river flooding, appropriate regulation and coordination between river and structures administrations are essential.

The level of lower bottom of bridge girder shall be higher than planed HWL plus specified additional space.

For the river with width of 50m or more, abutment shall not be placed in the lower level than HWL.

Ministry of Land, Infrastructure, Transport and Tourism JAPAN

National Institute for Land and Infrastructure Management 0 1 2 3 km

A:Vulnerable Pier

Narrow Width No footway

Lifeline Damage

Narrow Width A:Vulnerable Pier

A:Vulnerable Pier

Results of Vulnerability Study for M/P

Vulnerability Ranking on Possibility of Serious Damage Rank A: High Possibility Rank B: Medium Possibility Rank C: Low Possibility (Tentative, Need Detailed Evaluation)

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A:Soil Section

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3. Development of Nepal Own Seismic Design Code

MLIT Support Team

Design Standard Applied ・The design standards for bridges had not been developed, but it is concluded that 2010 Nepal Bridge Standards specified to use the Indian Road Congress (IRC) Code.

・It is specified that IRC code or AASHTO Code is to be applied for loading issues, and that IRC code is to be applied for the design.

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Nepal Bridge Standards-2067

MLIT Support Team

Recommendation: It is strongly recommended to develop the original code applicable and suitable for the earthquake situation in Nepal. If we do not have own original code, 1) the information of code is not enough and the

understanding of the back-data of each specified article becomes unclear.

2) no technology accumulation since the code shows a measure of current standard technology.

3) no interaction between research and practices 4) no education for engineers since to learn the

development/revision of codes is a good opportunity for training for engineers.

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Nepal Bridge Standards-2067

MLIT Support Team

Damage to Bridge

Lifeline:

Water Pipes

Weak and Non-

ductile Stopper

MLIT Support Team

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Discussion: It is recommended the design details of blocks should be modified including design force (to be primary) and bending/shear design.

Non-ductile Damage

In 2015 Nepal EQ

IRC: Section 219.9 Recommended Provision

MLIT Support Team

By IRC Code

By IRC Code

Performance-Based Design Concept

Type of Ground Motion

Medium EQ High Probability to Occur SPL 1: Prevent Damage

Type-I EQ

Inter-plate EQs Large EQ

Low

Probability

to Occur Type-II EQ

Inland EQs

Type-A

(Standard Br.)

Type-B

(Important Br.)

SPL 3:

Prevent Critical

Damage

(Non-Collapse)

SPL 2:

Limited

Damage for

Function

Recovery

Importance

TARGET SEISMIC PERFORMANCE (Japan)

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Not specified Target Performance ・Indian Road Congress (IRC) Code is not performance-based.

Discussion: It is recommended to use the performance-

based design concept.

MLIT Support Team

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IRC: Section 219.2 Z: Zone Factor

MLIT Support Team

Discussion: What zone value should be used

for Nepal based on IRC code?

By IRC Code

By NBC Code

Earthquake Observation Data: Nepal Earthquake of 25 April 2015 7.8Mw, 06:11:26 UTC,

28.15N 84.71E,

Depth 15km

Kanti Path,Kathmandu

Distance 14km

by CESMD (refer to

http://www.strongmotioncenter.org/)

40

MLIT Support Team

Possible Scenario Earthquakes 1) Mid Nepal EQ (M8.0） 2) North Bagmati EQ （M6.0） 3) Kathmandu Valley EQ （M5.7） PGA: 300～400gal (Observation : PGA 160- 170gal）

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Future Anticipated Ground Motion (JICA2002 Study)

MLIT Support Team

By JICA and MOHA

IRC: Section 19.5.5 R: Response Reduction Factor

41

?

Discussion:

The values for R without ductile

detailing seems to be too large for

substructures. Shear type failure is to

be prevented.

MLIT Support Team

By IRC Code

42

水平力

水平変位

△△

水平力

水平変位

耐震性能１耐震性能２耐震性能３

耐震性能を満足するエリア

耐震性能１に対する限界状態

耐震性能２に対する限界状態

耐震性能３に対する限界状態

SPL3 SPL2 SPL1

Lateral displacement

Late

ral Forc

e

Limit state for SPL1

Limit state for SPL2 Limit state

for SPL3

Ductility Design and Engineering Limit States

42

MLIT Support Team

Note: The ductility design means the

consideration of damage.

Development of Standard Substructure Drawings for Road Bridges

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Recommendation:

Coming 3 year DOR program: 1) New Road Construction: about 3000km

2) Upgrading of Roads

3) Bridge Construction: about 400 bridges

Standard superstructure drawings

for road bridges have been

published.

It is recommended to develop such

standard drawings for

Substructures considering the soil

conditions and the effect of scouring.

MLIT Support Team

45



4. Improvement of Roads in Rural/Mountain Areas

MLIT Support Team

Gorkha, Barpak Area: Countermeasures

45

Rangrung River

MLIT Support Team

Countermeasures: Risk assessment,

hazard mapping, preparation of heavy

machines to reopen, improvement works

with appropriate prioritization.

Roads in Mountain Areas: Ex. Road to Kulekhani: Slope Failure, Rockfalls

46

MLIT Support Team

Temporary Repair for River Crossing

47

River

Need Bridges

MLIT Support Team

Summary of Findings and Proposals/Recommendations Kathmandu Urban Area: Structures

1) Improvement of Functions (lanes and width) and Seismic Safety of

Bridges on the Emergency Transport Routes to make Resilient the Urban

Area. Bridge damage will be a bottleneck and cause the closure of Roads.

Replacement to New Bridges, Seismic Design, Seismic Retrofit,

2) Provision of Maintenance Technology and System (Inspection and

Repair of Bridges)

Deterioration/Scouring might cause serious damage at next events.

3) Improvement of Earth Structures (Reclaimed River areas, Inadequate

Drainage System)

Countermeasures for Vulnerable Embankment Section

4) Pedestrian Bridges

Replacement of Superstructures/Provision of Stopper/Connector

Rural Areas and Mountain Areas

1) Improvement of Lifeline Routes to connect Villages to Cities

2) Urgent Countermeasure for Reliable Road

Risk Assessment, Evaluation, Prioritized Improvement Works 48

MLIT Support Team

49

MLIT Support Team

Thank you very much

Shigeki UNJOH, Dr. Eng., PE, PWRI, MLIT E-mail: [email protected]

Visit PWRI web site: https://www.pwri.go.jp/eindex.html

mailto:[email protected]

https://www.pwri.go.jp/eindex.html

https://www.pwri.go.jp/eindex.html

findings and proposals/recommendations

Documents