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Workshop on Design for School Buildings
Chandani Chandra Neupane
Post-earthquake School Reconstruction Project
Lesson learnt from GorkhaEarthquake
Day : 1Session: 2
3
Gorkha Earthquake 2015
Gorkha Earthquake 2015
is followed by 465 numbers of aftershocks
with local magnitude ≥4
until 07 July 2016
4
Gorkha Earthquake 2015 (April 25)
Response spectra of ground motion
• Higher acceleration between 4 to 6 second• Unusual response spectrum as compared with
design spectrums.• More damaging effect to tall buildings (long period
structure)
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
SA,g
Natural Period,sec
Comparison of Elastic Spectrum (ξ = 5%)
90 360 NBC 105-1994 IS 1893-2002 UBC 97
5
Gorkha Earthquake 2015 (May 12- Aftershock)
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
SA,g
Natural Period,sec
Comparison of Elastic Spectrum (ξ = 5%)
90 360 Aftershock(Mw 7.3) NBC 105-1994 IS 1893-2002 UBC 97
Response spectra of ground motion
6
An aerial view of the village of Barpak, near the epicentre of the earthquake
David Ramos/Getty Images
7
Affected Area (31 districts)
D. Gautam & H. Chaulagain (2016)
14 districts
8
Loss: Gorkha Earthquake 2015
Deaths
8,686
Injured 16,808
Government Houses
• Fully Destroyed: 978
• Partial Destroyed: 3,021
Public Houses
• Fully Destroyed: 500,223
• Partial Destroyed: 269,156
5,000 schools
estimateddestroyed
9
Is damages/causalities less ?
• Both earthquakes occurred on a non-school day.
• Time of Earthquake (Mid day) : 11:56 am (NST) , 12:50 pm (NST)
• Less no of tall buildings
• Less population density in epicenter and severely hit region.
10
Earthquake Effects
• Four basic causes of earthquake-induced damage
Ground Shaking
Ground Failure
Fire
Tsunami
Secondary Disasters
Main Cause
Gorkha Earthquake (2015)
Gorkha Earthquake (2015)
Kobe Earthquake (1995)
Tohoku Earthquake (2011)
11
Ground shaking
People struggle for balance as the ground flails beneath themhttps://youtu.be/AJc5J2iDcRM
12
Ground failure
Vertical movement of ground which resulted in severe damages to road
13
Ground failure
Landslide on road to Kathmandu
Performance of Load bearing masonry
1515Complete collapse of a brick + mud mortar building
16
Damage in brick + mud mortar building and RCC buildings got no damage
(buildings in back)
RC Building performed better than masonry
17
Out of plane failure of gable wall
RC Building performed better than masonry
Out of plane failure
18
Heavy floor on weak
brick masonry wall
Corner crack, separation of wall
19
Serious damage in cultural heritage structures
Performance of RC Structure
21
Pancake collapse (Poor reinforcement detailing, poor quality of
construction material, faulty construction practices)
22
Soft and weak story Collapse (Poor reinforcement detailing, poor
quality of construction material, faulty construction practices)
23
17 story Park horizon apartment, Kathmandu
Significant damages in infill wall (non-
structural components)
Some minor damage to RC frame members
24
17 story Park horizon apartment, Kathmandu
Significant damages in infill wall (non-
structural components)
Some minor damage to RC frame members
Should tall building be designed for long-
period ground motion?
Should the seismic performance of non
structural components be considered in the
seismic design of tall building?
25
Out of plane failure of wall (Lack of bands) Large displacement in foundation led
tilting of building constructed in river bank
26Pounding Effect on nearby building
27Short column Effect
28
ACI Survey
30 High Rise (>7 storey)Engineered
146 Low Rise (<7 storey)Non-engineered
29
30
31
32
Poor construction practices
Poor geometric configuration
Long cantilever extension Floating columns
33
Poor construction practices
All the rebar are spliced at the same location in the column as marked in the diagram
34
Gongabu
Swayambhu
Sitapaila
Sankhu
Bhaktapur
Severely damaged buildings were concentrate on some areas in Kathmandu valley
35
Gongabu
Swayambhu
Sitapaila
Sankhu
Bhaktapur
Severely damaged buildings were concentrate on some areas in Kathmandu valley
Stronger ground shaking might be caused by site effect, basin effect, or topographic effect.
‘Seismic Microzonation Study’ should be properly carried out.
Building should be made more seismic resistant.
36
Lesson learnt
• Local site seismicity, geology and subsoil properties
More damage in the buildings on right side than on the left side of the road in Kathmandu, in Balaju area
37
• Construction and structural deficiencies
Wall failure(binding materials)
Column failure(Insufficient rebar and poor detailing)
Lesson learnt
38
• Attention to earthquake resistant features
• Proper maintenance
Infill wall failure(no bands )
Rusting(lack of maintenance)
Wall failure(no seismic features )
Lesson learnt
39
Lesson learnt
• Regulations, building by laws and seismic codes- revision and implementation
• Active interaction between earthquake engineers, structural engineers, seismologist, architects and government authorities
• Education of field engineers and construction practices
40
Lesson learnt
• Partial damaged structures should be replaced or retrofitted
• Transfer of Technology from Theory/Research to Practice
• Disaster Response
41
References
• http://www.seismonepal.gov.np/
• USGS
• http://www.nset.org.np/eq2015/
• http://www.dpnet.org.np/
• Gorkha (Nepal) Earthquake 2015, performance of masonry structures by D.C. Rai ,V. Singhal , S.L. Sagar, B.R. S, The masonry society.
• Learning from the Nepal 2015 Earthquake, S. Pujol, ACI Survey
42
References
• Lessons learned from the 25 April 2015 Gorkha Earthquake in Nepal, Prof. Pennung Warnitchai, AIT, 2015
• Common structural and construction deficiencies of Nepalese buildings, Gautam, D., Rodrigues, H., Bhetwal, K.K. et al., Innov. Infrastruct. Solut. (2016)
• Observation of building damage patterns in Kathmandu due to Earthquake, K. Acharya (2015)
• Lessons learned from the Nepal Earthquake 2015, T. Pokharel & H.M. Goldsworthy (2016)
43
Any Questions
44