60.-The Effects of the Meckering Earthquake on Engineered Brick
Structures in Perth, Western Australia
By G. A.
KATElVA
G. Kateiva & Partllers, Perth, W. Austra/ia
A BSTRACT
The developmellf oJ brick ellgineered
structures in Perfil , Western Australia
designed on the British Code CP 11 I
and 1101V according 10 lhe new
AlIstralian Brickwork Code is des-
cribed. The 1968 Meckerillg Earth·
Les EJJets du Tremblement de Terre
de Meckering sur la Technique de
Construction en Brique à Perth en
Australie de I'Ouest
La réalisatioll de la teclinique des
conslructions ell brique à Pertll,
Auslralie de I'Ouesl, reposait sur le
quake devas/ated tire coun/ry town
code Brilannique CP IlI: elle esl
bllildings. The earlhqllake Iras oJ a
conforme maintenant au nouveau
code Auslralien de la maçonnerie ell
brique. Le tremblemellt de terre de
magllitude of 6·9
011
lhe Richter
Scale, lVith lhe JOCIlS deplh oJ less
rhan 5 miles. However, lUla singlestorey brick build;'lgS s/ood up
reaSOll-
ably Irell to seismic shocks and
are described in lhe paper. The
seismic shocks ill Perth 80 miles
alVay were of intensity aboltl MM6.
The damage caused to buildings is
believed to GI110unt to several mil/ian
dollars. The tall brick structures have
displayed e/astic swaying m01ioll but
suffered no damage. This CO" be
attributed lo lhe cellular na/ure of
lhe buildings, main!y of residential
type. A nine-slorey oJJice building
a/50 of brick cons/ruclion lVi/h proper/y designed shear Il'a/ls is described
ill more detail. Fo/lowillg the eartllquake, reeommendatiolls are proposed
for eons/ruetion of eavity wal/s,
briek parapets, damp-proof membralles and the necessity of symmetry in arranging lhe shear walls
in lhe brick buildillgs. Cyclic teslillg
of brick wal/s and their intersections
is recommended.
Meckering de 1968 a dévasté les
immeubles de la vil/e de cette région.
Ce Iremblement de terre avait une
amplilllde de 6·9 (échelle Richter)
avec
U/J
épieemre d'une profondeur
inJériellre à 8 km. Cependant dellx
immeuhles de brique d'uf1 seul étage
011t assez bien résisté au choc sismique
et SOl1t décrits dans cet artide. Les
chocs sismiques à Perfh située à une
distance de 128 km étaient d'une
intensité d'envirolJ MM6. Les dommages causés aux immeubles s'é/event
à plusieurs milliolls de dollars. Les
constrllctions en brique de grande
hauteur ont subi un mouvemellt d 'oscillatiol1 mais aucuI1S dommages. Ceci
peut étre attribué à la nature
cel/ulaire des immeubles principalement de type résidentie/. U" im~
meuble à usage administratif de 9
é/ages construit également en brique
avec des murs de cisaillement COflvena-
blement conçus eSI décril de Jaçon
pllls détaillée. Des recommandations
suivent concernant les tremblements
de terre pour la constructiolt des murs
creux, des parapets en brique, des
membranes étanclles, la nécessité de
disposer avec symétrie les murs de
cisaillemellt dans les constructions
en briques. Des recommandations
concemant la nécessité du con trôle
périodique des murs de brique el de
leurs intersections sonl également
énlises.
365
Die Wirkungen des Meckering-Erdbebens auf Ziegelmauerwerk in
lngenieurbauten von Perth, WestAustralien
Die EnllVicklung mn Ziegelkonstruktionen at{{ Basis der Britischen Baul'orsclirift CP III bzIV. nach der neuen
Australischel1 Ziegelmauerwerk- Verordnung in Perlh , West-Australien , 1st
beschrieben. Das Meckering-Erdbeben
l'erIViistete 1968 die Gebaude der
liindlichen Sladl. Die S liirke des
Erdbebens enlsprach 6,9 der RichlerSkala, die Tiefe des Bebenzentrlllns
betrug weniger aIs 8 km. Aber zlVei
eingeschossige Ziegelbauten überstanden die Erdslõsse rec"t gut. Sie
sind im Ilorliegenden Aufsatz beschrieben. Die Erdst6sse VOII Pertll
halten in 128 km Entfernung noch
eine lntensiliit I'on rund M M 6. Der
an Gebiiuden entstandene Sclladen
wurde auf mellrere millionell DoI/ar
geschiitzt. Die hohen Ziegelbauten
sind zwar in ScllIvingwlg geraten,
aber olme Schaden geblieben. Das
kann der ze/lenartigen Natur der
Gebiiude zugeschrieben werden, hauptsiichlich bei den Wolmhiiusern. Ein
neunst6ckige GeschiiJlsgeballde ml~
zweckmiissig elltworfenen Ziege/wandkonslrllktionen hoher SchubJestigkeil
ist niiher besclzriehen. Nach dem
Erdbeben e1\lslanden EmpJehlungen
für die Kon struktioll 11011 Hohlmauerwerk, Ziegelstatzmauern, dampfdichten Schichten lInd far die Notwelldigkeit der symmetrischen Anordmmg
von Wiinden ;n Ziegelbauten, die
Ilohen Schubspanmmgen entgegemvirken sollen. Regelmiissige Prüfimg I'on
Ziegelmal/ern ulld ihren Sc/miltstellen
ist angernten.
I.
366
The Effects af the Meckering Earthquake an Engineered Brick Structures
I. ENGINEERED BRICK STRUCTURES
IN PERTH
During the post-war building period in Western Australia
a large number of dwellings was ereeted of whieh a good
proportion were built of clay brieks. The majority of
the brick buildings were single storey; some were three
storey with load-bearing walls, and a Ilumber were
multi-storey framed buildings with elay briek infill
walls. During this time the briekworks burned a variety
of wire-eut and pressed frog bricks. predominently in
red and salmon. Specifications did no! define any speeial
erushing strength , provided that the brieks were sound ly
burned, af good ringing sound, and reasuni1bly uniform
in size and colour: However, in about 1964 these oldfashioned brick kilns were gradually replaeed by automatie oil-fired tunnel kilns. The new proeess produced
bricks with astounding compressive strength properties af
between 5 000 and 11 000 Ibf/ in 2 range. This led engineers
and architects to realize the economic construction
possibilities, and this was lhe staft af brick structures af
faur and tive storeys in beight, and cast ;11 si/li reinforced
concrete slab floor construetion . With the Local Government Authorities' recognition of British Code C.P.III ,
engincers were able to raise the height of brick struetures
to eleven storeys, with lhe same conventional wall
thickness of 4t in. for internai , and 11 in . for externai
cavity walls. The concrete ftoor slab, in some cases, was
supported on both leaves of such eavity walls and expressed outside at eaeh fioor levei, and in others the
cavity was crossed at every third floor leveI. In many
instances it was desirable not to ex pose the concrete
slab in outer elevations, and a new technique was
developed to east the eonerete slab in to the pockets
formed in outer leaf of the cavity wall.
The building regulations in Western Australia require
that the externai walls of brick buildings be of eavity
construction. The width of the cavity is usually 2 in.
with a permitted maximum of 6t in. for single-storey
construction only.
In Perth outer walls ofbuildings are mainly ofexposed
or faeed brickwork, and therefore exposed to strong
weather elements of wind and rain during lhe winter
period. Large quantities of rainwater are being absorbed
by the outer skin of the cavity walls, and as a result of
moisture expansion, the growth of walls has been a
problem \Vith some brieks, particularly of low compressive strength. However, it is now possible to predict
such moisture expansion of bricks by a rapid laboratory
test, developed by the Melbourne Research Institute.
This method exposes brieks to a steam at atmospherie
pressure which measures the expansion. By applyillg
appropriate coeffieients a long-term brick expansion
can be predieted. These laboratory tests are frequently
performed, and a constant cheek is made of brick expansion. 8rick growth varies from .~ in. in 100 ft to an
excessive figure of Qver 3 in. in 100 ft. The variation
cannot be traced to locality or to a season of manufacture. Tt is quite common for two brick producers,
using identical plants and quarrying shale and clay from
pits almost adjacent, to burn bricks with a eompletely
different moisture expansion.
The effects of brick expansion, although quite rare,
are very dramatic, such as brick ba]ustrades warping
and twisling, long walls cracking at the corners, with a
perfeetly vertical craek through the perpends. A1though
it is thought that the bricks in the wall are restrained
from expansion because of large compressive stresses,
and also partly because of restraining by concrete in si/li
slabs, tbe fact remains lhat evidence of brick expansion
exists. Long walls are being avoided , particularly if they
are at right angles lo each other. Vertical control joints,
or floor-to-ceiling windows, are frequently llsed for
breaking such long walls into shorter elements, whieh
appear to solve the problem.
The height of briek struetures in Perth is restrieted
by an arbitrary limitation of 90 ft, whieh is considered
eompletely unjustified. Builctings of a height in exeess of
90 ft are, ar present, designed irrationally with bottomstorey walls of reinforced concrete. An exception to this
rule was made to a fourteen-storey briek building of
126 ft in height. However, the authorities requested that
the inner skin of the externai walls and the internai walls,
irrespective of low actual compressive stresses, be constructed 9 in. in lhickness.
The multi-storey briek eonstruction is being widely
used for apartment type bui ldings, hotels, dormitories,
and more recently for office buildings.
Great economies are being achieved with engineered
brickwork structures in Perth, one of the advantages
being that 110 elaborate machinery or equipment is
needed for the erection of briek struetures. Local building
experience has proved lhat a simple hoist is quile
adequate for lifting bricks, mortar and concrete. Orten
scaffoldillg is being dispensed with if there are baJconies
on externaI elevations. It has been proved that internai
walls of faced brickwork provide strong, durable and
almost maintenance-free internai finish; particlllarly
usefu l in tenancy type aceommodation. Lately it has
become a trend to paint the brieks externally and internally when desired. Tt is hoped that such treatment to
externa i brick walls will stand up to the strong Australian
Sll n.
In 1969 Australian Code C.A.47, '8riekwork in
Buildings', was published and is now being used for the
design , constrllction and supervision of reinforced and
unreinforeed briekwork in buildings. This Code has
been prepared in close collaboration with the Committee
responsible for C.P.III, and bears a close resemblanee to
the British Code, and to some extent the S.c.I.P. Code
of the USA.
Most of the present buildings in Perth of up to eleven
storeys in height are of load-bearing briek construction.
[n the eity bloek and the suburbs there are about thirty
buildings of between ten and eleven storeys in height
constrllcted with strllctura l brick, and abollt the same
number in the course of construction.
2. THE MECKERING EARTHQUAKE
On Oetober 14, 1968, an earthquake devastated the
town and most of the farm houses in lhe surrounding
area of Meckering in Western Australia. Tt disrupted
services in the town, cut off the 36-111. mail1 water supply
to the gold and nickel mining town of Kalgoorlie, and
interrupted lhe Transcontinental railway line service
linking the Western and Eastern Australian States for a
eonsiderable period.
Geologieally, this earthquake was of the greatest
intensity ever felt, and was the most damaging of any
earth disturbance recorded in Australia. A fault trace
was formed at least 27 miles long and the mobile eastern
G. A. Kateiva
block of the faull moved a maximum of 7 ft westwards
and 5 ft vertically upwards, and in places exposed the
actual fault plane aI the surface.
The epicentre has been located about 2 miles from the
township of Meckering aI the depth of the focus, less
Ihan 5 miles. The magnilude of the Meckering seismic
shock was estimated to be 6·9 on the Richter Scale. By
world standards this is quite moderate, but the shallow
focus depth macle the elfects quite vicious. Most of
the damage was done during the shaking, lasting 30 to
40 seconds. Houses were totall y destroyed up to 12 miles
east and 3 miles wesl of the faul!. A visit to the town
gives the impression cf wartime bornbing devastation.
Allhough lhe buildings constructed with brick masonry
suffered severe damage. and a number af such buildings
collapsed completely, there are two contrasting examples
which are quite outstanding. One, a brick building.
si ngle storey with a terra colta tile roof, suffered no
damage a1 ali, except for a few roofing tiles which \Vere
displaced or fell to the ground and were broken. The
general opinion, inc1uding that af the reinforced-concrete
and 5teel sympathizers, is lhat such ao occurrence was
just sheer luck or good fortune. Some mentioned that it
was due to brickwork af good const ruction.
The second example. a similar building consl ructed jusl
before the earlhquake occurred, when first inspected looked as though the damage was only superficial as disrupted
roofing tiles cou ld be seen from lhe distance, but 011
c10ser observ3tion the effects af seismic motion 00 a
grand scale and its results could be seen. Firstly lhe
internaI walls were broken up ioto segments af abollt
I yd 2 , with plaster intact and sti ll standing. The externai
wall , which is of a 2-in. cavity construction, exhibited
very little damage along its length, except that il was
cracked at the corners and below the windows. Some 01'
this cracking was due to a footing failure and there was
evidence of settlement. The intersections of internaI and
externai walls were completely sheared through verlically
and exhibited an inferior type of workmanship at the
intersections. A clean vertical crack up to door height
indicated the non-existence of bonding, apart from a
few courses at lhe door-head height where the bonded
bricks were broken. It is quite evident that as soon as the
intersection failed the swi nging motion of the externai
wall pounding against the internai walls resulted in lhe
breaking up of internai brickwork into segments but
remained standing beca use of the apparent tying action
of the roofing and ceiling timber members.
The above example illdicates, without doubt, lhe
importance of thorough bonding at the wall intersections. It also demonstrates the necessity of good bond
between the brick and the mortar. From both mentioned
case studies it is quile clear that a brick building, when
constructed with good-qualily brick and mortar joints,
and ifwell bonded at intersect ions, can withstand disturbing seisrnic forces. Tt is further evident that even cracked
masonry olfers considerable energy-absorbing qualities
and damping, particularly if the bond between bricks
and mortar is good, and the individual bricks are held
firmly togelher.
The earthquake was felt wilhin a radius of approximately 450 miles. Inlensities ranging from MM7 lo
MM9 were observed within 10 miles of the fault zene.
Perth, the capital of Western Australia, is 10cated
some 80 miles south-west of Meckering and the intensities were observed at about MM6. The damage to Perth
367
and metropolitan buildings was widely spread and
1110derate. Tall buildings swayed, causing power failures ;
lhe rubbing motion and the hammering aI the expansion
joints caused noise alld dust; severa I cracks were produced
in some older bui ldings; parapets partially collapsed;
facings and appendages fell to the ground and infill
walls of framed buildings cracked considerably. Ali this
damage, totalling millions of dollars, was done in a
malter of aboul 30 seconds in a cily believed to be free
and safe from seismic problems.
Following the earthquake ali buildings were carefully
surveyed by local government authorities for public
safety, and by the insurance assessors.
11 is interesling at Ihis stage to compare lhe damage
lo brick buildings of normal construction with tha! of
engineered brick construction. Brick buildings of normal
construction had walls cracked, the parapets swayed and
1110ved, particular1y when the shape and layout of the
buildings were unsuitable for seismic designo Old cracks
in domestic buildings became bigger, roof timbers moved
on the walls, causing damage to piaste r ceilings and wall
rendering. Tn brief, the weak structural points became
evident and lhe old and unsound brick walls cracked
considerably. The engineered brick buildings, however,
showed no damage at ali ; there were no signs of distress
at intersections of walls; no evidence of horizontal or
diagonal cracking in shear walls, or in any other walls.
The concrete slabs acting as diaphragms remained uncracked and intac\. Ali Ihis proved thal lhe engineered
brick buildings swayed elastically during the earthquake,
and lhe periods of vibration were observed up to 1
second.
As a case study I would Iike to mention a high-rise
office building which in character is somewhat different
from the usual cellular construction as it is constructed
with internai cross-walls of short length shaped as
double tee columns. The building is of nine storeys with
ground and first fioors occupied by car parking only. It
is perhaps \Vorth mentioning that this building proved lo
be very economical at a construction cost of S564.00
per square, equivalent lO flOO (sterling). The building
has three fasl lifls, carpeted and vinyl fioor coverings,
sprayed acoustic ceilings and basic lighting. The renls
for lhe building, which is located wilhin half a mile of
the heart of the City, are only one-Ihird 01' those normally
charged in a multi-storey office building. The developers
are more than satisfied with the handsome return of 18 %.
The fJoors are of in si/ti reinforced concrete of shallow
beam and slab construction. The bricks used in this
projecl are extruded IUnnel kiln perforated bricks of a
crushing strength F'm = 6000 Ibfjin 2 , laid in cemenl,
lime putty, sand mortar. The building, because of its
length, is divided into three sections each about 64 x
62 ft on lhe plan. The end sections contain the service
cores, lifts, stairs, and therefore are considerably stilf
and able to resist wind from ali directions. The middle
section, however, is of the same stifflless as end bays in
lhe direction across the building, but considerably less
stilf in the direction of the longitudinal axis. Fortunately
the earthquake occurred mid-morning on a Monday
Public Holiday, which meant that only a small percentage
of people were in the city buildings aI lhe time. However,
in our case study quite a few people were working in the
building, including consulting engineers and an architect,
who incidentally was responsible for the design of this
building.
368
The Effects of the Meckering Earthquake on Engineered Brick Structures
The occupants described the earthquake atrect on the
building as follows: 'A slight vibration was felt and at
first it was thought to be caused by a passing heavy truck,
Df
by structural steel workers erecting a neoo sigo
00
the
roor. The vibration increased until the whole building
began to tremble, followed by a distinct swinging motion,
associated with a very loud ímpact noise at about 1-
second intervals, The doors started to open and shut,
plaster dust began to fali at the expansion joints, The
noise continued and sounded like a giant sledge hammer
pounding the building.'
After the earthquake two independent consulting
engineers examined ali the walls in the building and could
not find any damage to the structural wall elements, nor
to the concrete slabs Of beams. Some cracking occurred
in the parapet walls which lacked more efficient buttressing and were weakened by the metallic strip fiashing.
Tt was clearly demonstrated that tall brick buildings
are not brittle, as is widely thought, and they are capable
Df resisting earthquake motioos to the paiot where they
remain uncracked. Should a
mOfe
severe earthquake
strike, it is thought that the load-bearing walls could
crack, but would be held together by re inforced concrete
slabs and remain safe.
It is my hope that the Meckering earthquake which
buildings and services to cope with possible future earthquakes. The design offices re-examined tbeir methods
and details of construction, The author's own feeling is
that a few items, such as the following, must be considered
for structures to be erected in earthquake-prone districts:
(I). The externai leaf of the ca vity wall needs to be
thoroughly tied to the concrete slab with non-corrosive
ties at each fioor leveI.
(2). The construction of parapets, long walls without
stitrness and wing wall should ali be reinforced with
piers, columns and buttresses.
(3). Detailing of damp-proof horizontal coursing
needs c.areful consideration as these form a horizontal
slip join!. New plastic sheet material appears to be
superior to metallic type sheeting beca use of better
bedding property. Mortar with inert materiais for waterproofness could also be very valuable provided the bond
between the brick and the mortar remains unaffected.
(4). The most important thing is to easure that the
buildings are symmetrical on both principal axes, and
have shear walls capable of transmitting the respective
horizontal forces 10 the foundations without developing
tension at any portion of the shear wall, and that the
shear stresses are not exceeded.
In concJusion I would like to recommend that some
research be made on the behaviour of engineered brick
shook Perth buildings can be regarded as a test indicating
that modern brick structures are quite capable of absorbing horizontal motions. The best proof is the performance of actual buildings when subjected to earthquake
cellular structures when subjected to cyclic loading,
especially after the formation of cracks in the walls. It
motions. Only from the shortcomings of various details
af construction after the seismic effect cao suggestions
lack ductility. The promoters of reinforced concrete and
and recommendatjons be made.
The 3uthorities and the professional institutions have
carefully examined lhe situation caused by the damage,
and at present are drafting rules for the design of
is often mentioned that brick structures are brittle and
structural steel have conducted a number of tests proving
the ductility of their structures. Therefore, it is my
suggestion that similar testing programmes on masonry
structures could show equally good results.