rapport christchurch eng v2

Guy BESACIER Christchurch NEW ZEALAND March 2011

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Report of the mission from 15th

to March 30 th

, 2011 in Christchurch

CONTENT

1. CONTEXT.......................................................................................................................................... 5

1.1 SEISMOLOGY........................................................................................................................... 5

1.1.1 Tectonic plates and fault of subduction zone ...................................................................... 5

1.1.2 The earthquake of February 22 th

, 2011............................................................................... 5

1.1.3 Historical data..................................................................................................................... 6

2. TARGETS OF THIS MISSION............................................................................................................... 7

3. ORGANIZATION OF THE EMERGENCY OPERATIONS CENTRE ............................................................. 8

4. OBSERVED DAMAGE ON FIELD ....................................................................................................... 11

1.2 NONSTRUCTURAL ELEMENTS................................................................................................ 11

1.2.1 Old brick masonry structures ............................................................................................ 11

1.2.2 Modern reinforced concrete structures ............................................................................ 13

1.3 STRUCTURAL ELEMENTS ....................................................................................................... 15

1.3.1 Heritage buildings ............................................................................................................. 15

1.3.2 Old constructions.............................................................................................................. 16

1.3.3 Industrial buildings............................................................................................................ 18

1.3.4 Modern constructions....................................................................................................... 20

1.3.5 Defective modern architecture ......................................................................................... 23

1.3.6 Strong modern architecture.............................................................................................. 29

1.4 FURNITURE ........................................................................................................................... 30

1.4.1 Shelving ............................................................................................................................ 30

1.5 CIVIL WORK........................................................................................................................... 32

1.5.1 Old steel frame bridges..................................................................................................... 32

1.5.2 Tramway rails ................................................................................................................... 33

1.5.3 Equipment on footpath..................................................................................................... 33

1.6 PROBLEMS OF LOCATION...................................................................................................... 34

1.6.1 Effects of soil liquefaction on roads and on footpaths ....................................................... 34

1.6.2 Effects of the Rock falls and Land slides............................................................................. 36

5. ACTIONS ON FIELD AFTER SAFETY ASSESSMENT............................................................................. 37

1.7 REMOVAL OF ESSENTIAL GOODS IN YELLOW BUILDINGS....................................................... 37


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1.8 ACTION OF ARMY.................................................................................................................. 38

1.9 ACTION OF POLICE AND CIVIL DEFENCE................................................................................. 38

6. RESULTS OF THE SAFETY ASSESSMENT ........................................................................................... 39

1.10 COLORS PLACARDS................................................................................................................ 39

7. CONCLUSIONS ON THE EFFECTS OF THE EARTHQUAKE................................................................... 42

1.11 REGARDING THE SOIL LIQUEFACTION.................................................................................... 42

1.12 REGARDING THE LOCATION OF THE BUILDINGS .................................................................... 42

1.13 REGARDING THE AESTITIC CRITERIA ..................................................................................... 42

1.14 REGARDING THE ANTI SEISMIC ARCHITECTURAL DESIGN ...................................................... 42

1.15 REGARDING THE QUALITY OF IMPLEMENTATION.................................................................. 42

1.16 REGARDING THE PRESENT SPECIFICATIONS........................................................................... 42

8. ORGANIZATION OF THE EMERGENCY OPERATIONS CENTRE ........................................................... 43

1.17 ADMINISTRATIVE FORMALITIES............................................................................................. 43

1.18 EQUIPMENT.......................................................................................................................... 43

1.18.1 Equipment of the engineers.......................................................................................... 43

1.18.2 Equipment of the bodyguards....................................................................................... 44

1.19 DAILY ORGANIZATION........................................................................................................... 44

1.19.1 Briefing......................................................................................................................... 44

1.19.2 Debriefing..................................................................................................................... 45

1.20 CONCLUSIONS....................................................................................................................... 46


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MAP 1 LOCALIZATION OF THE PRINCIPAL FAULT OF SUBDUCTION ZONE ................................................................... 5

MAP 2 LOCALIZATION OF THE NEW FAULT ................................................................................................................ 5

MAP 3 HISTORY OF THE PRECEDING LARGE EARTHQUAKES IN NEW ZEALAND SINCE 1848....................................... 6

MAP 4 LOCALIZATION OF THE EPICENTRE AND SCALE ................................................................................................ 7

MAP 5 ZONE 5 WITH THE RED POINTS ASSOCIATED EACH APPRAISED STRUCTURES ................................................. 9

PHOTOGRAPH 1 EMERGENCY OPERATIONS CENTRE................................................................................................... 8 PHOTOGRAPH2 RESCUE TEAM OF CHRISTCHURCH................................................................................................... 10 PHOTOGRAPH3 ELEMENTS OF DECORATION MADE OF REINFORCED CONCRETE .................................................... 11 PHOTOGRAPH 4 DAMAGED CAR DUE TO FALLING OF PARAPET ............................................................................... 11 PHOTOGRAPH5 FALL OF PARAPETS ON THE FOOTPATH ............................................................................................ 12 PHOTOGRAPH6 FALL OF BRICK CHIMNEY .................................................................................................................. 12 PHOTOGRAPH7 FALL OF PRECAST PANELS ON THE FOOTPATH .................................................................................. 13 PHOTOGRAPH8 OLD FRONTAGE IN FRONT OF A MODERN CAR PARK........................................................................ 14 PHOTOGRAPH9 COLLAPSE OF THE BELL-TOWER OF THE CATHEDRALE ..................................................................... 15 PHOTOGRAPH10 UNCONFINED STONES MASONRY ................................................................................................. 15 PHOTOGRAPH11 FALL OF UNREINFORCED MASONRY ................................................................................................ 16 PHOTOGRAPH12 GOOD BEHAVIOUR OF A 2 STOREY WOODEN HOUSE .................................................................... 16 PHOTOGRAPH13 OLD TRADITIONAL HOUSE WITH VENEER ...................................................................................... 17 PHOTOGRAPH14 WOODEN HOUSE WITH DEFORMED GROUND FLOOR .................................................................. 17 PHOTOGRAPH15 TOTAL COLLAPSEL OF THE ENTIRE SHOP ........................................................................................ 18 PHOTOGRAPH16 INDUSTRIAL BUILDING DUNCAN BUILT IN 1903 ........................................................................... 18 PHOTOGRAPH17 INDUSTRIAL BUILDING INTENDED FOR DEMOLITION..................................................................... 19 PHOTOGRAPH18 MIXED STRUCTURE: STEEL FRAME + PRECAST PANELS.................................................................. 19 PHOTOGRAPH19 HOUSE STRIPPED OF ITS BRICK VENEER......................................................................................... 20 PHOTOGRAPH20 COLLAPSE OF EXTERNAL BRICK VENEER ........................................................................................ 20 PHOTOGRAPH21 REINFORCED CONCRETE MASONRY............................................................................................... 21 PHOTOGRAPH22 BUILDING CONSTRUCTED OF PRECAST PANELS............................................................................. 21 PHOTOGRAPH23 BEAM HAVING LOST ITS SUPPORT AND RESTING ON A TRUNK OF VEHICLE................................... 22 PHOTOGRAPH24 FLOOR SUPPORTED BY VEHICLES.................................................................................................... 22 PHOTOGRAPH25 GOOD DESIGN AND IMPLEMENTED OF REINFORCED CONCRETE CORBEL.................................... 22 PHOTOGRAPH26 BUILDING WITH 6 SIDES, UNSUITED TO THE TORSIONAL STRESSES ............................................. 23 PHOTOGRAPH27 2° TILT ° OF THE HOTEL "GRAND CHANCELLIER" ........................................................................... 24 PHOTOGRAPH28 SIGNIFICANT DAMAGES IN THE CAR PARK ADJACENT THE HOTEL ................................................. 25 PHOTOGRAPH29 RUPTURE OF THE GLAZED FACADES OF SHOP AND OFFICE BUILDING.......................................... 25 PHOTOGRAPH30 TYPICAL DAMAGE OF THE SHORT COLUMNS.................................................................................. 26 PHOTOGRAPH31 INADEQUATE CONFINEMENT OF CONCRETE.................................................................................. 26 PHOTOGRAPH 32 SEISMIC JOINT RESPONSIBLE OF DAMAGE IN UNREINFORCED MASONRY................................... 27 PHOTOGRAPH33 DEFICIENCY OF THE CROSS-BRACING BY FAILURE IN TRACTION OF THE BAR ............................... 27 PHOTOGRAPH34 STEEL K CROSS-BRACING LINKED WITH REINFORCED CONCRETE FRAME IN A CAR PARK .............. 28 PHOTOGRAPH35 COLLAPSE OF AN INDUSTRIAL BUILDING ....................................................................................... 28 PHOTOGRAPH36 MASONRY WALL WEAKENED DUE TO VERY POOR QUALITY OF MORTAR .................................... 29 PHOTOGRAPH37 POWERFUL STRUCTURAL FRAME................................................................................................... 29


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PHOTOGRAPH38 COLLAPSE OF FURNITURE WITHOUT CROSS BRACING .................................................................. 30 PHOTOGRAPH39 UNSECURE STORAGE OF HEAVY MATERIALS .................................................................................. 30 PHOTOGRAPH40 UNSUITABLE FURNITURE TO STORE FILES AND BOTTLES ............................................................. 31 PHOTOGRAPH41 BLACK WATER TANK DAMAGED BY ITS FALL ................................................................................. 31 PHOTOGRAPH42 COLLAPSE OF A COVER DUE TO FAILURE OF ANCHORS.................................................................. 32 PHOTOGRAPH43 BUCKLING OF THE HANDRAIL SUPPORT .......................................................................................... 32 PHOTOGRAPH44 SHEARING OF THE RAIL .................................................................................................................. 33 PHOTOGRAPH 45 DAMAGE OF FOOTPATH AND EQUIPMENT.................................................................................. 33 PHOTOGRAPH 46 DEFORMED AND RAISED FOOTPATH .............................................................................................. 34 PHOTOGRAPH47 DAMAGE TO THE ROADS AND BURIED SERVICES ........................................................................... 34 PHOTOGRAPH48 SAND BOILS IN KILMORE ................................................................................................................. 34 PHOTOGRAPH49 DAMAGE TO ROAD AS RESULT OF LATERAL SPREADING................................................................ 35 PHOTOGRAPH50 THE MUDDY SAND BOILED TO THE SURFACE BY WATER UNDER PRESSURE.................................. 35 PHOTOGRAPH51 DAMAGE BY ROCK FALL TOWARDS MOUNT PLEASANT AND IN RED ROCK .................................... 36 PHOTOGRAPH52 ROCKS FELL ON THE ROAD ............................................................................................................. 36 PHOTOGRAPH 53 BRIEFING WITH ANNE MACKENZIE AND NEVILLE HIGGS .............................................................. 37 PHOTOGRAPH 54 SETTING UP PROTECTION BY ARMY STAFF ................................................................................... 38 PHOTOGRAPH 55 REMOVAL OF CARS........................................................................................................................ 38 PHOTOGRAPH56 GREEN PLACARD............................................................................................................................ 39 PHOTOGRAPH57 YELLOW PLACARD ......................................................................................................................... 39 PHOTOGRAPH58 RED PLACARD ................................................................................................................................ 39 PHOTOGRAPH59 CONCENTRATION OF THE DAMAGE TO THE DOWNTOWN AREA................................................... 40 PHOTOGRAPH60 OVERALL PICTURE CHRISTCHURCH AND ITS SUBURBS................................................................... 41 PHOTOGRAPH61 HOOLIGAN HAMMER ....................................................................................................................... 44 PHOTOGRAPH62 NEED OF DANGER TAPE THEN SAFETY FENCE................................................................................ 45


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1. CONTEXT

1.1 SEISMOLOGY

1.1.1 Tectonic plates and fault of subduction zone

Map 1 Localization of the principal fault of subduction zone

1.1.2 The earthquake of February 22 th

, 2011

The earthquake of February 22nd, 2011 was caused by the rupture of a previously unknown fault.

Map 2 Localization of the new fault


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1.1.3 Historical data

Map 3 History of the preceding large earthquakes in New Zealand since 1848


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Map 4 Localization of the epicentre and scale

A first earthquake magnitude 7.1 occurred in September 2010 follow-up of another on 22 February at

13h51 local time, with magnitude 6.3 then an aftershock the very same day at 15h with magnitude 5.3

The hypocentre of February 22 event was to only 5 km of depth to 10 kilometers to the south-east of

Christchurch close to the port of Lyttelton.

On September 2010, 30 000 tons of muddy sands were ejected by liquefaction which had to be removed

whereas in these February are 200 000 tons which were emitted causing, one week after the

earthquake, of clouds of dust raised by winds up to 70 km/h.

A number of people deceased in the February event amounts to 235 of which a hundred in a

construction built in 1979, it collapse and then caught a fire and another 90 died in a school of English

language.

2. TARGETS OF THIS MISSION

• Take part as volunteer with the other structural engineers in the safety assessment of damaged

buildings

• Study the organization of the Emergency Operations Centre

• Improve the anti-earthquake design by taking into accounts the damages observed on field.

• Provide recommendations for the future in order to reduce the risk of natural disaster.

• Meet Australian, British and New Zealand engineers.

• Compare New Zealand regulation with European regulation.


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3. ORGANIZATION OF THE EMERGENCY OPERATIONS CENTRE

An Emergency Operations Centre (EOC) was installed in the ART GALLERY building close to the

downtown area.

Photograph 1 Emergency Operations Centre

The organization of the relief envisaged three levels of intervention

• City council

• District

• National

Following this event, the national office installed in Wellington moved to Christchurch to support the

district office CANTERBURY

Following initial evaluation, two zones within the downtown area were established according to the level

of damage:

• Yellow zone accessible with a blue pass

• Red zone accessible only to the people provided with a red pass (personal document with

limiting dates signed by the manager of the EOC)


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Each ZONE is broken up into BLOCKS numbered in order to better manage the data collected on

field.

Map 5 Zone 5 with the red points associated each appraised structures

A safety cordon guarded by the ARMY was set up around the yellow zone and another around the red

zone at the heart of the downtown area.

POLICE FORCE patrollers the red zone of day and night to prevent looting.

They also take part in the evacuation of the vehicles parked in many car parks with members of the Civil

Defence; the cars were relocated out of the safety cordon so that the owners can recover them.

The mission of the New Zealand and Australian RESCUE TEAMS is to assist the teams of POLICE FORCE

and STRUCTURAL ENGINEERS in their engagement on field. They also take part in the evacuation of the

valuable and essential goods from the artisanal shops and commercial company offices.

Each “SAFETY ASSESSMENT” team consists of two CIVIL DEFENCE safety members assisting two

STRUCTURAL ENGINEERS at the time of the safety assessment and at the time of the evacuation of the

essential goods (computers, invaluable goods etc.) by the owners or tenants of the buildings.


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Photograph2 RESCUE TEAM of CHRISTCHURCH

A permanent radio connection is ensured with the Team Leader located at the Emergency Operation

Centre (EOC)

During the inspections of buildings, one safety member accompanies the two engineers and the other

one remains outside

Precise instructions are given:

• radio operator calls every 30 seconds

• in case of aftershock, remain in the building in order to avoid being a victim of the falling

parapets, precarious masonries or glazing

The level 1 evaluation consists a visual rapid analysis relating to the following elements:

• Soil and Foundation

• Structural elements

• Non-structural elements

• Environment and neighbours

It is typically completed by external inspection rules the followed by a Level 2 inspection.

The level 2 evaluation includes internal inspections.


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4. OBSERVED DAMAGE ON FIELD

1.2 NONSTRUCTURAL ELEMENTS

1.2.1 Old brick masonry structures

• Cracking of the parapets made of unreinforced masonry or poorly reinforced concrete

Cause: The poor quality of concrete did not protect the reinforcement from corrosion

Consequence: Falling of the parapets in frontage and side wall

Photograph3 Elements of decoration made of reinforced concrete

Recommendation: remove all the old reinforced concrete parapets and replace them by light

material parapet

Photograph 4 Damaged car due to falling of parapet


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Photograph5 fall of parapets on the footpath

Recommendations: remove all the parapets made of unconfined or unreinforced masonry and replace

them by light material parapets or secure existing parapets.

• Case of brick chimney :

Many chimneys collapsed either into the house or outside.

Photograph6 Fall of brick chimney

Recommendation: to replace all the brick chimneys by well anchored light chimneys


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1.2.2 Modern reinforced concrete structures

• Case of precast panels made of reinforced concrete used as balustrade but badly fixed

Reason of the damages: under dimensioning of anchors

Consequences: rupture of fixing anchors for the precast panels and falling of panels.

Photograph7 Fall of precast panels on the footpath

Recommendations: remove all the precast panels, restrength their anchors or replace them by lighter

elements.

• Case of the heritage facade linked to modern constructions

The modern constructions hidden behind the frontage of old constructions made of unconfined or

unreinforced masonry are very current in many countries (Italy, Greece, Turkey, Portugal, France etc.) in

particular in the large tourist cities from Lisbon to Nice and also in Christchurch

Under pretext of trying to preserve the historical inheritance, the architects succeeded in persuading the

local authorities to preserve these frontages which show interesting aesthetic characteristics and try to

generally associate them with reinforced concrete structure; unfortunately the result is often

unsatisfactory from the point of view of global earthquake behaviour. The connection of two

constructions is often precarious and the old material having not a good dynamic behaviour at the time

of an earthquake disintegrates generating falls which often make victims. Such is thus the price to pay to

see non earthquake resistant heritage buildings still or almost upright.


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This modern car park is built with precast reinforced concrete and is hidden behind an old frontage in

brick masonry

Photograph8 old Frontage in front of a modern car park

The tests with the sclerometer conducted at the time of the visit prove that compressive strength of the

concrete of the framework of the car park is of excellent quality: 60MPa for the pre-casted units and 50

MPa for the concrete cast in place on the other hand the supported frontage has many observed

defects: segregation, aggregates rolled instead of crushed

Consequence: Fall of unreinforced masonry on the footpath

Recommendation: demolish the frontage and to replace it by construction adequate to resist seismic

loads.


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1.3 STRUCTURAL ELEMENTS

1.3.1 Heritage buildings

• Case of the vulnerable monuments in stone masonry

Reason for the damages: lack confinement of masonry:

Consequences: Collapse of a part of the CHRISTCHURCH Cathedral.

Photograph9 Collapse of the bell-tower of the Cathedrale

Photograph10 unconfined stones masonry

Recommendation: reinforce all the heritage constructed of bricks and stones masonry.


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1.3.2 Old constructions

o Poor behaviour of brick masonry structures

Consequence: Falling of unreinforced or unconfined masonry walls.

Photograph11 fall of unreinforced masonry

o Good behaviour of wooden constructions.

Photograph12 Good behaviour of a 2 storey wooden house

The wood is light material and the construction is ductile therefore can resist strong earthquake


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o Ductile behaviour of the wooden framework build at the beginning of the century but poor

behaviour of masonry walls used as fire protection.

Photograph13 Old traditional House with veneer

Recommendation: to demolish the masonry and replace by boarding made of light material veneer

o Ductile behaviour of a 2 storey wooden house.

Photograph14 Wooden House with deformed ground floor

Recommendation: repair the house and improve it with strong cross bracing.


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o Poor behaviour of a shop with brick masonry walls

In spite of a light roof reducing the seismic demand, the poor quality of the mortar caused total collapse.

Photograph15 Total collapsel of the entire shop

1.3.3 Industrial buildings

o Good dynamic behaviour of a construction in brick masonry

Reasons: regular shape in plan and in elevation, massive walls and openings are far from the angles.

Photograph16 Industrial building DUNCAN built in 1903

No damages were observed


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o Very poor behaviour of an industrial workshop built in 1935

Reasons of damage: unconfined masonry, heavy roof made of very heavy steel frame, lack of reinforced

concrete link belt.

Photograph17 Industrial building intended for demolition

Recommendation: demolition or set up steel columns supporting the steel frame of the roof, set up steel

cross bracing, demolish masonry walls and replace them with precast panels like below:

o Good behaviour of an industrial building in a steel frame and precast panels.

The steel frame is associated with precast panels anchored to the ground.

Photograph18 Mixed structure: steel frame + precast panels

Recommendation: set up a cross bracing linked with the steel frame and set up a device to limit

horizontal displacement at the top of the precast panels.


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1.3.4 Modern constructions

o Ductile behaviour of modern houses in wood side with brick “veneer"

Cause damages: masonry is neither reinforced nor confined

Consequence: The house is still standing but all the external veneer collapsed.

Photograph19 House stripped of its brick veneer

Photograph20 Collapse of external brick veneer

Recommendation: set up wooden frame and wooden board to replace brick veneer.


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• Reinforced concrete masonry structures

The behaviour is very good thanks to the many vertical reinforcements of large diameter.

Photograph21 reinforced concrete masonry

• Case of reinforced concrete precast panels

Advantages: Good dynamic behaviour in spite of the important mass concerned, earthquake resistant,

rapid implementation.

Photograph22 Building constructed of precast panels


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• Case of the poor reinforced concrete corbel

Rupture of reinforced concrete corbel supporting the beams on which a floor rests.

Cause N°1: reinforcement was not in conformity with the specifications (the higher concrete cover of the

main reinforcement is 150 mm instead of 30 mm, and in more it misses stirrups)

Consequences: shear stresses are not bearable by the concrete which bursted

Cause N°2: the central beam rested only on two defective corbels

Consequence: collapse of the entire floor occurred crushing the vehicles below

Photograph23 Beam having lost its support and resting on a trunk of vehicle

Photograph24 Floor supported by vehicles

• Good design of reinforced concrete corbel

Photograph25 Good design and implemented of reinforced concrete corbel


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1.3.5 Defective modern architecture

o Case of an office building of 14 storeys

Cause: defect of anti seismic architectural design; the building is not powerful with respect to resistance

in torsion.

Consequences: all the connections between columns and beams are damaged; repairs following the

earthquake in September were in progress at the time of the earthquake in February.

Photograph26 Building with 6 sides, unsuited to the torsional stresses

Recommendation: structural engineers should not accept to calculate any shape because most of

architects are not aware of seismic loads. Demolition of this building is recommended.

One fundamental principle is to avoid torsion during earthquake thanks to shear walls at the right

position. The dynamic behaviour of this building will never be satisfactory even after reparation.


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Case of the badly damaged hotel "Grand Chancellier"

• Cause N°1: Serious defect of architectural anti seismic design: the tower is connected on

a part to a car park which disturbed its mode of vibration, the collision generated serious

damages in the elements connecting the two parts

• Cause N°2: Poor quality of the soil and foundation: According to certain information, the

hotel would have been inclined 2° because of a problem of liquefaction of the soil

• Cause N°3: Lack of stirrups in the critical zone at the top of column : spacing between

steel bars is three times too large (photograph 28)

• Cause N°4: overloaded in compression due to seismic loads in both principal directions

Consequences: rupture of columns, rupture of floor, ruptures of beams, sinking and tilting of the

building, collapse of staircases.

Photograph27 2° tilt ° of the hotel "Grand Chancellier"


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Lack of stirrups in the critical zone = > Buckling of the main reinforcements, rupture of the floor

Photograph28 Significant damages in the car park adjacent the hotel

The problem will be to carry out a demolition without damaging constructions around.

• Falling of the glazed facades

The modern architecture with substantial glazed facades is responsible for many injuries because

glass is a fragile material which does not support significant deformations.

Photograph29 Rupture of the glazed facades of shop and office building

Recommendation: Special design should take into account of the great deformations due to the

seismic movements.


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• Damages of the columns at the car park level of the CASINO due to "short column effect"

Cause: poor anti seismic design, very rigid columns of small height compared to their neighbours

were damaged because the horizontal seismic forces concentrated on them.

Photograph30 Typical damage of the short columns

Recommendation: repair the short columns and separate them from the walls in order to find

again same stiffness as the other columns.

• Damage engraves reinforced concrete column

Cause: lack of stirrups in the critical zone near the connection beam-column

Consequences: bursting of the concrete of the top of the column.

Photograph31 inadequate confinement of concrete

Recommendation: increase confinement of concrete by reducing the distance between stirrups.


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• Case of the anti-seismic joint between rigid modern construction and old flexible brick

construction

Cause of damages in the old building: the creation of a seismic joint between the new car park and

the old building allowed at the time of the earthquake, a horizontal displacement of the old building

constructed with unreinforced masonry. Being detached from its previous neighbour, it lasts an

abutment and broke.

Photograph 32 seismic joint responsible of damage in unreinforced masonry

Comment : Attached masonry buildings are usually less vulnerable than detached buildings.

• Case of cross-bracing using high strength bars

Cause of rupture: under sized of the resistant section in traction of the bars

Photograph33 Deficiency of the cross-bracing by failure in traction of the bar

Recommendation: increase the size of the cross-bracing

• Case of the cross-bracing by steel frame


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Benefit: recognized effectiveness when it is well dimensioned and positioned at the right place but

requires sometimes a replacement after use.

Photograph34 steel K cross-bracing linked with reinforced concrete frame in a car park

Recommendation: choose the right places of cross bracing to prevent torsion, add damper.

• Case of an industrial brick building with steel frame roof

Cause: rupture of walls constructed of neither reinforced nor confined masonry

Consequence: collapse of the whole building

Photograph35 Collapse of an industrial building

Recommendation: identify similar construction and retrofit them


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• Poor behaviour of unreinforced brick masonry

Cause: poor quality of mortar which crumbles on touch

Consequence: the wall broke down on the public footpath

Photograph36 Masonry wall weakened due to very poor quality of mortar

Recommendation: confine the masonry by a reinforced plaster on both sides or demolish it and rebuild

in reinforced masonry

1.3.6 Strong modern architecture

o Case of a 2 storey office

Very good dynamic behaviour during the earthquake, the shear walls made of reinforced masonry

functioned well and the structure which associates double beams and a column is intact.

Photograph37 powerful structural frame


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1.4 FURNITURE

1.4.1 Shelving

• Case of a piece of furniture having been damaged

Cause: lack of cross bracing

Consequence: the rupture of the aquariums resulting in a loss of fish.

Photograph38 Collapse of furniture without cross bracing

Recommendation: provide a guide line for provider of furniture

• Case of a storing shelf supporting very heavy objects of which some fell during the earthquake

Photograph39 unsecure storage of heavy materials

Recommendation: provide restraints to protect the storekeepers and to prevent damage to the

goods


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• Case of bar and office furniture’s

Photograph40 unsuitable furniture to store files and bottles

Recommendation: provide restraints to secure objects at the time of earthquake.

• Case of water tank on roof

Cause of damage: lack of restraints resulting in water tank falling of its support

Photograph41 Black water tank damaged by its fall

Recommendation: install restraints, reduce the volume of the tank


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• Case of poor anchoring of cover which collapse

Cause: under designed anchoring which failed by rupture of steel in shear,

Reason: the two buildings have not the same period of vibration therefore one side of supports should

be able to slide horizontally.

Consequence: The cover fell down

Photograph42 collapse of a cover due to failure of anchors

Recommendation: identify all similar elements and reinforce their anchors

1.5 CIVIL WORK

1.5.1 Old steel frame bridges

Large deformations of the soil caused serious damages to the bridges.

Some structural elements could not resist compressive load and buckled.

Photograph43 Buckling of the handrail support


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1.5.2 Tramway rails

A horizontal movement of soil sheared the rails of the tramway

Photograph44 Shearing of the rail

1.5.3 Equipment on footpath

Photograph 45 Damage of footpath and equipment


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1.6 PROBLEMS OF LOCATION

1.6.1 Effects of soil liquefaction on roads and on footpaths

The roads and the footpaths became deformed, cracks appeared in the streets

Photograph 46 Deformed and raised footpath

Photograph47 Damage to the roads and buried services

Photograph48 sand boils in KILMORE

200 000 tons of silty sand “boiled” to the surface causing problems to the whole district.


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Lateral spreading took place at edges of rivers and the sea

Photograph49 damage to road as result of lateral spreading

Phenomenon of sand boiled to the surface

Photograph50 the muddy sand boiled to the surface by water under pressure

Extract from the document "solid-facts-christchurch-liquefaction.pdf "


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1.6.2 Effects of the Rock falls and Land slides

o Fall of rocks on buildings

Cause: Lack of regulation prohibiting construction of public buildings and dwelling houses at the foot of

unstable rock cliffs,

Consequence: destruction of buildings and human losses.

Photograph51 Damage by rock fall towards Mount Pleasant and in Red Rock

Recommendation: establish a minimal distance of safety to build at the bottom of a cliff when its

material does not show good mechanical characteristics of sufficient cohesion.

o Fall of rocks on the roads

No protection is provided with respect to the road users vis-a-vis to falls of rocks

Photograph52 Rocks fell on the road

Recommendations: purge the rock slopes, set up nets retaining the rocks, construct shelter to protect

from rock fall


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5. ACTIONS ON FIELD AFTER SAFETY ASSESSMENT

1.7 REMOVAL OF ESSENTIAL GOODS IN YELLOW BUILDINGS

One month after the earthquake, many companies needed to recover their computers, files etc.

A special building owner’s access safety briefing is organized every day; it gave the specific hazards that

are identified as follow:

• Tripping hazards - broken pavement etc.

• Overhead falling hazards - parapets, glass, loose timer, brick, iron, tiles etc.

• Gas - should not smoking in the area

• Electricity – treat all wires as live

• Water – basements in particular could be full of water which may include sewage

• Chemicals etc.

• Lack of support – trap door may be loose and there may be hole in floors

• Don’t climb or rubble

• Asbestos and other dust in the building could be injurious to health – wear mask

• Rotting organic material

• Bodies – if you find a body or part of body, return in the same route as you entered and

call 111 and wait for the POLICE to arrive

• Walk in the centre of the roads, looking out for high falling objects

• If you feel unsafe or feel the building is unsafe, then withdraw from the area

Photograph 53 Briefing with Anne MACKENZIE and Neville HIGGS

The owners have to wear yellow or orangejacket, hand hat and get a temporary blue pass from EOC.


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1.8 ACTION OF ARMY

Many doors, windows and glazed wall were damaged; ARMY was in charge of setting up temporary

wooden protection to prevent looting.

Photograph 54 Setting up protection by ARMY staff

1.9 ACTION OF POLICE AND CIVIL DEFENCE

The organization of removal cars took a long time due to many reasons.

• Identify the owner of each car

• Get the keys of the cars

• Perform safety assessment

• Identify emergency exit way

• Remove debris on the exit way

• Provide emergency battery

• Organize co-ordination between Poilce staff, Rescue team and Structural engineer when everything is

ready

Photograph 55 Removal of cars

Police staff has to check inside the car


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6. RESULTS OF THE SAFETY ASSESSMENT

1.10 COLORS PLACARDS

At the time of the inspection by the engineers, coloured placards are stuck to the doors of the buildings

• Green placard stating that access into the building is UNRESTRICTED

Photograph56 GREEN Placard

• Yellow placard stating that access or entry into the building is RESTRICTED, subjected to

conditions

Photograph57 YELLOW Placard

• Red placard stating that building should not be entered or occupied

Photograph58 RED Placard


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Recommendation: use a waterproof sheet to protect the placard from the rain and a permanent marker

able to resist to sunshine.

Map of the result of the established investigations updated on April 29th 2011

DETAIL OF THE DOWNTOWN AREA

Photograph59 Concentration of the damage to the downtown area

Many buildings concentrated with the downtown area, built in brick masonry neither reinforced and nor

confined were very much damaged.

Certain reinforced concrete buildings fell or were very much damaged for reasons related to poor

material being used in the construction or built with weak reinforced concrete when the specifications

was not as severe as now and for reasons related to a poor anti-seismic architectural design.


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OVERALL PICTURE OF THE TOWN AND IT SUBURB

Photograph60 Overall picture Christchurch and its suburbs

The historical downtown area was affected the most by the earthquake mainly because of the high

vulnerability of old buildings constructed in unreinforced masonry or stone work.

In the suburbs, the mud sand invaded certain suburban and caused damages in many houses.

Further assessment was carried out on the buildings placarded RED leading to a recommendation

notified on a BLUE form as either of the following:

• Total demolition

• Partial deconstruction

• Possible repair


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7. CONCLUSIONS ON THE EFFECTS OF THE EARTHQUAKE

1.11 REGARDING THE SOIL LIQUEFACTION

The soil made of a mixture of silt and sand, combined with a high level ground water, while being

liquefied, contributed to the damages. The roads were deformed, the bridges were damaged, the large

volumes of muds appeared on the surface in the old marshy zones where houses had been built, the

buildings were sinking and tilting, the lateral spreading appeared at edge of river, the vehicles were

covered in mud and the drainage and sewer systems were damaged.

1.12 REGARDING THE LOCATION OF THE BUILDINGS

The location of the buildings at the bottom of the cliff or at the top of the cliff caused serious disasters

and casualties. The permit building legislation should be more rigorous in relation to effects of

earthquake or tsunami.

1.13 REGARDING THE AESTITIC CRITERIA

A significant number of victims were also due to architectural issues because of fall of non-structural

elements such as the parapets, the element of decoration, and the glazing: the beautiful one is not

earthquake resistant when it is very heavy, fragile and also badly anchored. Ruptures of anchors from

very heavy precast elements are also at the origin of fall causing casualties.

There are two categories of parapets: those which already fell and those which may fall at the time of

the next earthquake; the great question is to know if measures of prevention will be taken to make sure

that the second category disappears

1.14 REGARDING THE ANTI SEISMIC ARCHITECTURAL DESIGN

The old architecture from the beginning of the 20th

century performed well during the earthquake in

particular the industrial buildings constructed with brick masonry. Nevertheless considerable timber

structures with a brick veneer were damaged. The modern architecture has choosen large windows and

glazed walls; they must be checked in order to adopt if necessary constructive specifications adapted to

this fragile material which doesn't resist high deformation.

1.15 REGARDING THE QUALITY OF IMPLEMENTATION

The quality of construction of precast reinforced concrete is now very good, that was not always the case

with the reinforced concrete and the masonry in the structures built a few tens of years ago.

1.16 REGARDING THE PRESENT SPECIFICATIONS

Certain old reinforced concrete buildings are vulnerable because of large spacing between the stirrups in

the critical zone therefore the concrete is not correctly confine and because of poor quality of

compressive strength of concrete. It would be necessary to launch a recognition campaign of

reinforcement using steel detector and sclerometer in order to identify those which do not answer the

new constructive specifications then reinforce them. All anchors should also be checked.


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8. ORGANIZATION OF THE EMERGENCY OPERATIONS CENTRE

1.17 ADMINISTRATIVE FORMALITIES

The daily formalities are:

• Selection of structural engineers and contractors

• Signature of the contracts defining the rights and obligations between Consultant and

Christchurch City Council

• Constitution of the teams from

o two structural engineers whose Team leader is chartered

o two safety guards from the civil defence

• Training the methodology of level 1 and 2 safety assessment

Comment: a guide line would be useful with examples of filled forms.

1.18 EQUIPMENT

1.18.1 Equipment of the engineers

• Safety shoes

• A hand hat with a strap

• A yellow jacket

• A back bag

• Dust respirator and mask anti odour with double filter

• A level (one meter)

• A hammer

• A compass

• A manual flashlight

• A head light fixed on hand hat

• Safety goggles

• Gloves

• A sclerometer (Hammer test) optional

• A map of the city

• A security pass

• A mobile phone

• Red, Yellow, Green placards

• Level 1, Level 2 and Blue forms

• A writing pad

• A black pen and a permanent marker

• A roll of scotch tape

• A digital camera

• A water bottle


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1.18.2 Equipment of the bodyguards

• A hand hat with strap under chin

• Safety shoes

• Red or orange overalls

• A back pack with water tank

• A head light + a torch

• A multifunction knife

• A “hooligan” hammer of 1 meter (special foot of hind fireman to see photo 55)

• A rope of 20 m

• Snap hooks - Carabiners

• “Danger” Tape of 50 m

• A transmitter – Receptor

• A whistle

• A compressed-air horn

• Gloves

• Knuckles

• Safety goggles

• A dust respirator and a mask with double filter

Photograph61 Hooligan hammer

1.19 DAILY ORGANIZATION

1.19.1 Briefing

The briefing takes place every morning at 8h with a precise program:

Assignment of missions to the teams by type of construction

• Commercial buildings

• Dwelling houses

• Car park

• Heritage buildings

Assignment of mission according to the level of evaluation

• Level 1: a brief external visit

• Level 2: Visit of confirmation in the strategic buildings

• Level 3: Blue form for the inspected building placarded in red leading to a

recommendation as either

� total demolition


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� partial deconstruction

� possible reparation

1. Assignment of 2 Safety Guards per teams of 2 structural engineers

2. Assignment of the vehicles for the teams going to suburbs and the yellow zone

3. Supply of the food (drink, sandwich, fruit etc.) for the lunch

4. Checking of the equipment before going on field

Photograph62 Need of danger tape then safety fence

Recommendations: at the time of the evaluation level 1 and level 2 in zone of suburbs out of the

perimeter of safety, it is necessary to envisage stakes being able to support the danger tape while

waiting for the installation of safety fences.

It is necessary to demolish quickly all the cracked and unstable elements if these are likely to fall on the

public.

The owners of old houses of the beginning of the 20th century complain to lose their inheritance and the

owners of shops complain to lose their sales turnover. Perhaps the media sufficiently did not inform the

public of the complexity of the situation and the risks in the event of an aftershock.

The preventive demolitions made it possible to ensure a minimum of safety but there were still many

danger zones with unstable sections of wall obstructing the investigations and the evacuation of the

vehicles one month after the earthquake. The needs for safety fence are enormous in this kind of event

and the danger tapes are not sufficient to ensure an impassable barrier; it could be possible to minimize

it if the teams of demolition intervened earlier.

Fortunately that the afters chocks were not very strong because many constructions in unreinforced or

unconfined masonry weakened by the two preceding tremors are not completely collapsed but they

remain dangerous in the event of a strong afters chock.

The security instructions are respected strictly on the field.

1.19.2 Debriefing

The debriefing takes place every evening at 18h, it makes it possible to collect the comments of the

teams, to give a progress report on the advance of the evaluations in order to plan the following day, to

plan the work.


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1.20 CONCLUSIONS

An exemplary organization of crisis management was installed within a very short time and proved that

the co-operation with the army and police civilo-police is very effective.

Many of volunteers could bring their assistance.

Many testimonials of support on behalf of children and inhabitants motivated the teams.

Although the administrative data processing is heavy and slows down the interventions of the teams of

demolition and the teams of evacuation, the situation is under control.

Recommendations to improve protection of the public:

� Provide supports for "DANGER" tape at the time of the establishment of the safety cordon

� Improve the coordination between the evaluations of level 2 and 3 (Blue Card)

� Reduce the time to install the safety fence in suburbs

� Provide a checklist of the equipment necessary before going on field for each team

The great challenge for the city of Christchurch is to find solution of strengthening of old structures in

order to reduce their current vulnerability and to ensure a reliable dynamic behaviour in the future.

Another challenge relates to the taking into account of the liquefaction of the soil: how to minimize the

effects on the buried roads, services, the structures and the buildings.

However, there is a remaining risk suspends some: that of the vulnerability of the city vis-a-vis to a

tsunami, indeed CHRISTCHURCH is built at the edge of sea on a flat ground which facilitates

displacements in the bicycles but it could suffer enormous damage if a wave penetrated inside as it was

the case with Banda Aceh in Indonesia and recently the town of Kesennuma in Japan.

I want to note that the breakfasts, lunches and dinners of an excellent quality were served gracefully for

all the members of the EOC staff.

I thus thank all the personnel serving these meals including the delicious coffees and other drinks.

I particularly also thank Anne MACKENZIE who introduced me when I arrived the first day, as well the

engineers TEAM leader as Dejan NOVAKOV, Simon MONNING, Paul FAIRBAIRA and all Safety Guards as

Shane BOYLE who took care of us during the expertises on the field.

This mission was the richest which has been given to me to live for 12 years as both for human and

professional issues and I give the first Award at the EOC of Christchurch.

Wrote* in PARIS on April 20th

, 2011

Guy BESACIER

* Special thanks to Dejan NOVAKOV for his collaboration in this English version

rapport christchurch eng v2

Documents

modern constructions

old constructions

defective modern architecture

strong modern architecture

old brick masonry structures

christchurch content

old steel frame bridges

nonstructural elements