rapport christchurch eng v2
DESCRIPTION
Report of the post-seismic mission on March 2011 in ChristchurchTRANSCRIPT
Guy BESACIER Christchurch NEW ZEALAND March 2011
1
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
2
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
3
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
4
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
5
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
6
1.1.3 Historical data
Map 3 History of the preceding large earthquakes in New Zealand since 1848
Guy BESACIER Christchurch NEW ZEALAND March 2011
7
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
8
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)
Guy BESACIER Christchurch NEW ZEALAND March 2011
9
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
10
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
11
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
12
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
13
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
14
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
15
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
16
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
17
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
18
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
19
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
20
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
21
• 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
Guy BESACIER Christchurch NEW ZEALAND March 2011
22
• 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
Guy BESACIER Christchurch NEW ZEALAND March 2011
23
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
24
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"
Guy BESACIER Christchurch NEW ZEALAND March 2011
25
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
26
• 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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
27
• 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
Guy BESACIER Christchurch NEW ZEALAND March 2011
28
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
29
• 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
Guy BESACIER Christchurch NEW ZEALAND March 2011
30
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
31
• 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
Guy BESACIER Christchurch NEW ZEALAND March 2011
32
• 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
Guy BESACIER Christchurch NEW ZEALAND March 2011
33
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
34
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
35
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 "
Guy BESACIER Christchurch NEW ZEALAND March 2011
36
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
37
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
38
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
39
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
40
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
41
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
42
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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
43
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
44
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
Guy BESACIER Christchurch NEW ZEALAND March 2011
45
� 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.
Guy BESACIER Christchurch NEW ZEALAND March 2011
46
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