Prepared By: Sarah Bettinger
Occupancy: Residential
Year Built:
Height: 24 ft
Number of stories: 2
Stories below ground: unknown
Size:
Original Code: IS:1893-1984 (also Sikkim Building Construction Regulations of 1991?)
Modification: Unknown
Year Modified:
Code of Modification:
Lateral Load System: Frames with Masonry Infill
Other Load System:
Vertical Load System: Unknown
Other Vertical Load System:
Foundation : Unknown
Other Foundation :
Country: India
State: Sikkim
City: Chungthang
Street:
Latitude: 27.60434
Longitude: 88.646597


House of BDO

Earthquake Information

 

 

Earthquake Date 40804
Moment Magnitude 6.9
Epicentral Distance 60
Local Intensity VIII Other
Site Description
PGA Lateral None (g)
PGA Vertical None (g)
SaT
Ground motion recording stations Earthquake motions were recorded at Gangtok and Siliguri by strong motion accelerographs operated by DEQ, IIT Roorkee. The PGA values recorded at these locations are 0.15g and 0.20g, respectively (Rai, 2012).
Distance to station None
Station Latitude None
Station Longitude None
Ground Motion Summary The US Geological Survey (USGS) indicates that the earthquake was located at 27.723N, 88.064E with a focal depth of 19.7km, in the India-Nepal border region. The quake occurred at the boundary between the India and Eurasian plates, in a region known for seismic activity between the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT).

 

Damage Information

 

 

Performance summary

The building did not collapse but the frame joints of the building were badly damaged. There was severe cracking to the masonry infill walls in one direction, and out-of-plane collapse of the infill walls in the other direction.

Damage state description

The main damage was the out-of-plane failure of the infill masonry block wall. Additionally, there was damage to the beam-column joints on the first story of the building and at the intersection of the stairwell and second floor slab.

Summary of causes of damage

1. The block masonry wall was not sufficiently reinforced and connected to the structural frame to prevent the out-of-plane collapse. 2. Severe damage occurred at the beam-column joints on the first story of the building. 3. Additional damage occurred at the intersection of the stairwell and the second floor slab.

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete Poor quality concrete is typical for construction in this area.
Reinforcing steel Smooth reinforcing bars are typical for construction in this area.

ExecutionNotesContribution to Damage
Conveyance/placement of concrete
Rebar
Field variance with design documents
OtherNotesContribution to Damage
Other Factors Construction Quality

Configuration

Plan IrregularitiesNotesContribution to Damage
Torsion
Perimeter boundary
Diaphragm
Out-of-plane offsets in lateral resisting system
Non-orthogonal systems

Vertical IrregularitiesNotesContribution to Damage
Soft story
Weak story
Geometric variablility of lateral resisting system
In-plane discontinuity of lateral resisting system
Mass distribution
Setback
Change in stiffness

OtherNotesContribution to Damage
Other Factors Configuration

Lateral Load Resisting System‐General

StrengthNotesContribution to Damage
Overall lack of strength

StiffnessNotesContribution to Damage
Extreme Flexibility

Load PathNotesContribution to Damage
Collectors/Struts
Anchorage of nonstructural elements
Out-of-plane capacity of walls
Diaphragm chords
Diaphragm openings

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-General

Lateral Load Resisting System‐Frames

ColumnsNotesContribution to Damage
Shear strength
Flexural strength
Axial load ratio
Vertical load columns drift capacity
Interference of frame action by infill

BeamsNotesContribution to Damage
Strength relative to columns
Shear controlled behavior
Continuity of longitudinal reinforcing
Loss of vertical capacity
Interference of frame action by infill beams

JointsNotesContribution to Damage
Interior
Exterior
Corner

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Frames

Lateral Load Resisting System‐Shear Walls

ShearNotesContribution to Damage
Diagonal tension/compression
Sliding Shear
Flexure/shear

FlexureNotesContribution to Damage
Compression zone buckling capacity
Discontinuity of wall
Boundary reinforcing fracture/buckling
Boundary Reinforcing at openings

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Shear Walls

Lateral Load Resisting System‐Infills

InfillsNotesContribution to Damage
Unreinforced Inadequate reinforcing of masonry infill walls.
Interference with frame action
Out of plane Out-of-plane failure of masonry infill walls in one direction.
Attachment to framing Inadequate attachment of masonry infill walls to concrete framing members.

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting Systems-Infills

Lateral Load Resisting System‐Other

FoundationsNotesContribution to Damage
Liquefaction
Pounding
Surface Rupture

OtherNotesContribution to Damage
Pile/Pier tension capacity

MiscellaneousNotesContribution to Damage
Spread footing capacity
Other Factors Lateral Load Resisting Systems-Other-Foundations

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting Systems-Other-Misc

Repair and Retrofit Information

 

Type of Retrofit or Repair

Unknown

Other Retrofit or Repair

Unknown

Performance Level

Unknown

Hazard Level

Unknown

Retrofit or Repair Code

Unknown

Other Retrofit or Repair Code

Unknown

Lateral Analysis

Unknown

Other Lateral Analysis

Unknown

Design Strategy

Unknown

Retrofit Summary

Unknown

References

 

http://www.eeri.org/wp-content/uploads/Sikkim-EQ-report-FINAL_03-19.pdf
Murty, C. V. R. and Sheth, A., ed. The Mw 6.9 Sikkim-Nepal Border Earthquake of September 18, 2011. Learning from Earthquakes. EERI Special Earthquake- February 2012.


http://db.concretecoalition.org/static/data/6-references/INDI002_Reference_2.pdf
Sheth, A. and Murty, C. V. R.,"Concrete Coalition Project Earthquake Damage Examples from India." Earthquake Engineering Research Institute. Oakland, California. 25 June 2012.


http://www.nicee.org/Sikkim_EQ_2011_Slide.pdf
National Information Center on Earthquake Engineering, 2011. 2011 Sikkim Earthquake: Effects on Built Environment & a Perspective on Growing Seismic Risk, http://www.nicee.org/Sikkim_EQ_2011_Slide.pdf (July 10, 2012).


http://www.nicee.org/current%20Science.pdf
Rai, D. C., et. al., 25 May 2012. The M 6.9 Sikkim (India-Nepal Border) earthquake of 18 September 2011, Current Science , vol. 102, no. 10, 1437-1446 .


http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0005wg6/
United States Geological Survey (USGS), 2012.Magnitude 6.9- India-Nepal Border Region http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0005wg6/ (25 July 2012).