Post-Earthquake Assessment of Buildings Connecting Database Compilation, Mobile Data

Transmission and GIS Visualization

Sujan Raj Adhikari, Gopi Krishna Basyal, Surya Narayan Shrestha,Suman Pradhan

National Society for Earthquake Technology – Nepal

USMCA2015The 14th International Symposium on New Technologies for Urban

Safety of Mega Cities in AsiaOctober 29-31, 2015

Radisson Hotel, Kathmandu, Nepal

25th April, 2015, at 11:56 local time, 7.6 magnitude earthquake with the epicenter in Barpak, Gorkha District, 80 km northwest of Kathmandu

Gorkha Earthquake was followed by thousands of aftershocks including M6.6 and M6.7 within 24 hours and Mw7.3 (ML6.7, Department of Mines and Geology) on 12 May 2015 which caused additional damage and casualties.

Gorkha Earthquake, 2015

Gorkha Earthquake, 201541 Municipality, >400 VDC

Deaths:

9,256

Injury:

22,326

Affected Populati

on:

8 million

Source: NPC,2015Data: As of May 21,

2015

Building Damage

:

513,411

Housing located in different zones will be damaged differently

Different types of buildings will be damaged differently due to different construction, materials and techniques

Building Damage Assessment

• Tentative Estimation of building damage

• To understand Failure Patterns

• To identify Damage Grades

Damage Stone Masonry

Tilting of RC frame

General Building Information

1.Use 1.a residence 1.d commerce1.b office 1.e factory1.c school 1.f hospital

2. Type 2.a stone, adobe 2.d reinforced concrete 2.b masonry/wooden roof 2.e steel structure2.c masonry/concrete roof

3. Damage 3.a no damage 3.d Heavy damage, 3.b Slight damage 3.e Very Heavy damage 3.c Moderate damage 3.g Destruction

4. Plan 4.a square 4.c L-shaped4.b rectangular 4.d complex

5. Soil 5.a soft 5.c rock5.b hard 5.d sloping

6. Photographs

Google Earth Imaginary

Chautara MunicipalitySundhupalchok District

Google Earth Imaginary

Chautara MunicipalitySundhupalchok District

field paper

Guideline for Detail Damage Assessment

Refer post disaster damage assessment guidelines published by DUDBC to develop the questionnaires for assessment

Mobile Technology in data collection

Section A contains building identification data (id, city, address, ownership, no of resident etc.),

Section B contains building technical characteristic (no of stories, age of building, primary occupancy etc.),

Section C contains geotechnical hazard,Section D contains data related to the structural type Section E contains Damage grade, recommendations and building Photographs

Building Digitization on Google Earth

Linking database

Mobile Data

Excel Data

Field Paper

GISMap

Google Earth

Building Digitization

Outcome

Building Typology

Ward wise number of buildings

1 2 3 4 5 6 7 8 9 Total

Adobe         3         3

Bamboo    1 1           2

Brick Block In Cement1   11 9 11   20 1   53

Brick Block In Mud    2       6     8

RC Frame8 14 278 55 14 5 189 32 21 616

Stone In Cement  3 4 3 3   1   1 15

Stone In Mud414 505 194 332 519 389 296 335 577 3561

Timber Frame        1   1   2 4

Mix     18 9 1   17     45

Grand Total423 522 508 409 552 394 530 369 601 4308

Outcome

Building Typology VS

Damage Grade

Damage GradeWard wise number of buildings

1 2 3 4 5 6 7 8 9 TotalNone   1 12 7 1 1 9   3 34Grade1 2 8 101 34 23 3 49 5 7 232Grade2 9 17 134 42 18 4 97 13 15 349Grade3 5 6 20 8 2   27 10 11 89Grade4 47 93 29 68 43 28 66 103 144 621Grade5 360 397 212 250 465 358 282 238 421 2983Total 423 522 508 409 552 394 530 369 601 4308

Outcome

Building Typology VS

Recommendation

RecommendationWard wise number of buildings

1 2 3 4 5 6 7 8 9 TotalNone   1 12 16 3 1 11   5 49Repair 11 24 231 66 39 7 142 18 20 558Retrofit 7 7 26 16 3   50 15 16 140Demolish 405 490 237 311 507 386 322 335 560 3553Further Evaluation     2       5 1   8Total 423 522 508 409 552 394 530 369 601 4308

Outcome

take-home message

• Proper utilization of technologies will help to collect pre and post-disaster information in short span of time.

• This study will mentor Chautara Municipality to differentiate the building which are possible to repair/ retrofit and which needs to be demolish.

• This study positively support the government to developed reconstruction strategy plan.

Thank you for your time and attention.