This building was a 4-story reinforced concrete structure that was constructed before the modern NZ building code was adopted (NZS 4203:1976). After the February 2011 earthquake, this building was severely damaged and subsequently demolished. The building...

Prepared By: Edwin Lim
Occupancy: Commercial
Year Built: 1950
Height:
Number of stories: 4
Stories below ground: 0
Size:
Original Code:
Modification: Unknown
Year Modified:
Code of Modification:
Lateral Load System: Moment Frame and Shear Wall Combination
Other Load System:
Vertical Load System: Slabl_Beams_Columns
Other Vertical Load System:
Foundation : Unknown
Other Foundation :
Country: New Zealand
State: Canterbury
City: Christchurch
Street: 202 Gloucester Street
Latitude: -43.530025
Longitude: 172.641363


 

4-Story Building

Earthquake Information

 

 

Earthquake Date 40596
Moment Magnitude 6.1
Epicentral Distance 6.663
Local Intensity VIII MMI
Site Description Site Class D (Kam et al, 2011)
PGA Lateral 0.531 (g)
PGA Vertical 0.5 (g)
SaT
Ground motion recording stations Christchurch Cathedral College (CCCC), Christchurch Botanic Gardens (CBGS), Christchurch Hospital (CHHC), Christchurch Resthaven (REHS)
Distance to station None
Station Latitude None
Station Longitude None
Ground Motion Summary The February, 2011 South Island, New Zealand earthquake occurred as part of the aftershock sequence of the M 7.0 September, 2010 Darfield, NZ earthquake. The February earthquake involved oblique-thrust faulting at the easternmost limit of previous aftershocks and, like the main shock itself, is broadly associated with regional plate boundary deformation as the Pacific and Australia plates interact in the central south island, New Zealand. This latest shock was significantly closer to the main population center of Christchurch, NZ than the September main shock, in the vicinity of several other moderate sized aftershocks located east of the main rupture zone of the 2010 event. There is no specific structure directly linking this event to the main fault of the 2010 main shock, although there have been numerous aftershocks along generally east-west linear trends extending east from the end of the previous rupture. The north or north-east trends to the possible fault planes and the oblique thrust faulting mechanism as seen in the focal mechanism solution may reflect an association with similarly-trending faults previously mapped in the Port Hills region, just south of Christchurch. The February aftershock had an extremely short duration of 8 seconds of strong motion shaking (USGS).

 

Damage Information

 

 

Performance summary

The stiff infilled RC frame and RC core-walls at the south side of the building contributed to a significant plan irregularity. This irregularity resulted in the torsional demand on the northern frame due to east-west seismic shaking (extracted from Kam et al, 2011).

Damage state description

The major damage to the building could be found in the north frame of the building where the columns exhibited severe shear failure. Meanwhile there were some diagonal and hairline cracks on the south frame infill walls. Diagonal shear cracking, with the possibility of some flexural cracking, was observed in the shear wall in the perimeter of the staircase (refer to plan layout, page 3). It was not clear which story this crack occurred on. In addition, the building was subjected to extensive non-structural damage to office contents and moderate damage to operational component cabinets.

Summary of causes of damage

General and main causes: 1. Plan irregularities 2. Lack of transverse reinforcement in columns Crack on internal shear wall: 1. Restraint condition from stairwell leads to shorter section of shear wall

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete
Reinforcing steel

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 Contribution of the location of shear wall, stiffer infilled frame system at the south frame, and possibly communication tower on the roof.
Perimeter boundary Only small re-entrant
Diaphragm Only small opening area
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 Communication tower on one side of the roof
Setback
Change in stiffness

OtherNotesContribution to Damage
Other Factors Configuration Cantilever canopy

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 Possibility of captive column

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 Inadequate connections: diagonal cracks (X shape)
Corner

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Frames

Lateral Load Resisting System‐Shear Walls

ShearNotesContribution to Damage
Diagonal tension/compression Diagonal crack in shear wall in stairwell area
Sliding Shear
Flexure/shear Diagonal crack in shear wall in stairwell area

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 Cracks on the infill walls
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
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

Performance Level

NA

Hazard Level

NA

Retrofit or Repair Code

NA

Other Retrofit or Repair Code

Lateral Analysis

NA

Other Lateral Analysis

Design Strategy

Retrofit Summary

References

 

http://db.concretecoalition.org/static/data/6-references/NZ002_Reference_3.pdf
Kam, W.Y., Pampanin, S., and Elwood, K., 2011. Seismic Performance of Reinforced Concrete Buildings in the 22 February Christchurch (Lyttelton) Earthquake,Bulletin of the New Zealand Society for Earthquake Engineering,44, 239178.


http://www.geonet.org.nz/earthquake/historic-earthquakes/top-nz/quake-14.html
GeoNet, 2011.M 6.3, Christchurch, February 22 2011. (Accessed: 12 July 2012).


http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usb0001igm/
United States Geological Survey (USGS), 2011.Magnitude 6.1 - SOUTH ISLAND OF NEW ZEALAND, (Accessed: 12 July 2012)


http://strongmotioncenter.org
Center for Earthquake Strong Motion Data (CESMD), 2011.New Zealand Earthquake of 21 February 2011, (Accessed: 10 July 2012).


Kam, W. Y., 2011. Select photos from 21 February 2011 Christchurch, New Zealand Earthquake. Earthquake Engineering Research Institute Photo Library, Oakland, CA.