The Himilchuli Hotel is a seven-story hotel located on a steep slope. The building was so sufficiently damaged during the 2011 Sikkim earthquake that it was ordered to be demolished. At the time of the earthquake, the infill partition walls at the second...

Prepared By: Sarah Bettinger
Occupancy: Hotel
Year Built: 1990
Height:
Number of stories: 7
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: Unknown
Other Load System:
Vertical Load System: Other
Other Vertical Load System: RC Beam and column
Foundation : Other
Other Foundation : Laterally connected to hill at 4 levels.
Country: India
State: Sikkim
City: Gangtok
Street: 31-A National Highway
Latitude: 27.342494
Longitude: 88.606426


 

Himalchuli Hotel

Earthquake Information

 

 

Earthquake Date 40804
Moment Magnitude 6.9
Epicentral Distance 68
Local Intensity VI MMI
Site Description
PGA Lateral 0.15 (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 was significantly damaged in the 2011 Sikkim earthquake and ordered to be demolished.

Damage state description

The Himilchuli Hotel suffered soft story effects on the 2nd floor, which was exacerbated by the partition walls having been removed for interior redecorating. Levels other than the 2nd floor showed minor damage. Good framing of evenly spaced columns well connected with a beam grid helped the building's behavior and prevented complete collapse.

Summary of causes of damage

1. The building was narrowest at the base due to being built on a hill. 2. The failure of the building was caused by soft story effects at the 2nd floor. Temporary removal of partition walls on the 2nd floor contributed to the collapse. 3. Small column size leading to high axial stress ratio, coupled with corroded reinforcing bars and deteriorated concrete, caused all columns to fail in shear, undergoing concrete spalling and buckling of bars at both ends.

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete Concrete is typically mixed by hand, with no formal mix design.
Reinforcing steel Questionable quality reinforcing steel.

ExecutionNotesContribution to Damage
Conveyance/placement of concrete Inadequate cover for reinforcing steel.
Rebar
Field variance with design documents Only designed for 5 stories, 7 stories were built.
OtherNotesContribution to Damage
Other Factors Construction Quality Building poorly maintained, so concrete was deteriorated and reinforcing was corroded (Sheth and Murty, 2012).

Configuration

Plan IrregularitiesNotesContribution to Damage
Torsion
Perimeter boundary Building was built on a hill, so was narrowest at the base (Sheth and Murty, 2012).
Diaphragm
Out-of-plane offsets in lateral resisting system
Non-orthogonal systems

Vertical IrregularitiesNotesContribution to Damage
Soft story Soft story condition at second level; partition walls had been temporarily removed on that floor (Sheth and Murty, 2012).
Weak story
Geometric variablility of lateral resisting system
In-plane discontinuity of lateral resisting system
Mass distribution Uniform across the floor, but least at base of building and highest at top of building.
Setback
Change in stiffness

OtherNotesContribution to Damage
Other Factors Configuration

Lateral Load Resisting System‐General

StrengthNotesContribution to Damage
Overall lack of strength Small column size

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 All columns experienced shear failure on 2nd floor (Sheth and Murty, 2012).
Flexural strength
Axial load ratio Small column size led to high axial stress ratio (Sheth and Murty, 2012).
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 Poor detailing
Exterior Poor detailing
Corner Poor detailing

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
Interference with frame action
Out of plane
Attachment to framing

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 No foundation failure
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

None (demolished/abandoned)

Other Retrofit or Repair

Building Scheduled to be demolished

Performance Level

Unknown

Hazard Level

Unknown

Retrofit or Repair Code

Unknown

Other Retrofit or Repair Code

Lateral Analysis

Unknown

Other Lateral Analysis

Design Strategy

Retrofit Summary

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.pptx
Sheth, A. "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).