This building was a 5-story RC frame-wall building with multiple elements failing in a brittle fashion. It was comprised of six one-way RC frames in the north-south direction and several coupled and single RC walls acting predominantly in the east-west di...

Prepared By: Edwin Lim
Occupancy: Commercial
Year Built: 1969
Height:
Number of stories: 5
Stories below ground: 0
Size:
Original Code:
Modification: none
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: 271 Madras Street
Latitude: -43.529204
Longitude: 172.642241


 

5-Story Building

Earthquake Information

 

 

Earthquake Date 40596
Moment Magnitude 6.1
Epicentral Distance 6.711
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 lateral resisting system in the east-west direction appeared to be severely damaged. In addition, it was likely that the RC frames resisted a significant portion of the lateral load in the north-south direction and torsional load from the east-west shaking. (extracted from Kam et al, 2011)

Damage state description

The coupled walls in the internal grid line had severe damage on the coupling beams of the lower three stories. A settlement of the foundation of approximately 400 mm was observed beneath the core walls. This resulted in the shear failure of the foundation ground beam with evidence of liquefaction. A shear failure in the beam-column joint was also observed in the center of rigidity of the north side frame. (extracted from Kam et al, 2011)

Summary of causes of damage

Damage to the core wall was the result of several factors: 1. Lightly reinforced with plain rebar coupling beam 2. Foundation failure due to liquefaction Damage to beam-column joint was the result of several factors: 1. Huge lateral and torsional load 2. Failure of wall system and foundation that 'dragged' the RC frames inward 3. Unreinforced beam column-joint (extracted from Kam et al, 2011)

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete
Reinforcing steel Smooth reinforcement bar

ExecutionNotesContribution to Damage
Conveyance/placement of concrete
Rebar Lightly reinforced coupling beam
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 Shear failure in the foundation beam and in north frame
Continuity of longitudinal reinforcing
Loss of vertical capacity Drop of foundation beam
Interference of frame action by infill beams

JointsNotesContribution to Damage
Interior
Exterior Shear failure (shear-wedge)
Corner Shear failure (shear-wedge)

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Frames Damage in coupling beam

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
Other Factors Lateral Load Resisting Systems-Other-Foundations Foundation failure

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

The building was subsequently collapsed in an aftershock on 13 June 2011 (Kam,et al)

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://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).


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).


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