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Introduction
Melbourne's Royal Exhibition Building,
erected for the Melbourne International Exhibition of
1880-1, is one of Australian most prominent and historic
public buildings. It is a monumental structure that stands
in the Carlton Gardens near the centre of Melbourne as a
testimony to the Victorian spirit of enterprise and industry
in late nineteenth century Australia. The building, now
graced with a Royal Charter, was also the setting for the
Federation ceremonies in 1901 that marked the birth of
Australia as a nation. As the venue for many events and
exhibitions during it's long life, the building and garden
surrounds represent an important link with Australia's
cultural life.
Designed by noted Australian architect,
Joseph Reed, it is a fine early example of the use of timber
in the structure and finish of a large classical style
building in Australia. Architectural features include the
Florentine dome, deep arched doorways and the classical
edifice, considered to be Reed's finest. The main building,
the hall with its dome and transepts, is all that remains of
the original complex, which included two large annex wings
and a variety of temporary structures. Today, the building
is acquiring a new partner, with construction of the new
Denton Cocker Marshall designed Victorian Museum within the
adjacent gardens .
Description
The main building, erected in line with
Gertrude Street, Fitzroy has a frontage of 151m to the
principal walk across the gardens. The deep archway of the
main entrance, that faces south to Spring Street, is capped
by a fanlight 12.1m in diameter and flanked by towers that
rise 30.3m. Beyond and above the towers, the dome rises to
66.6m. At tower level, enclosed by parapet walls is a
terrace, originally designed for promenading around the
dome. The interior volume comprises a long and commanding
nave and more modest transepts. Both are flanked by aisles
and overlooked by continuous and well lit galleries. The
crossing of nave and transepts is dominated by the inner
ceiling of the octagonal dome, and its supporting
buttresses, pendatives and drum. The columns, floors,
ceilings and structure of the nave, transepts and crowning
dome are all constructed of timber while the surrounding
facades and dome supporting structure are masonry.
All of the internal timber work, except
the naturally finished floors, was originally richly painted
in Victorian patterns and colours. Now restored, this gives
a sense of movement and gaiety to the building while
punctuating many of the otherwise flat surfaces, and
reinforces the long lines and vista of the nave. It works to
make the interior of the building appear larger and more
grand.
Structural Description
Notwithstanding the powerful lines of
the dome externally, the dominant structure upon entering
the building is the long roof and supporting lines of
columns in the nave and transepts. The main and repetitive
roof elements are tied trussed arches that spring from the
top of each of the solid Oregon columns in the upper gallery
tier. The trussed arches support the exposed roof and
ceiling structure of under-purlins, rafters and a board
lined ceiling. Columns in the lower tier and further lines
of columns behind them support the timber framed and boarded
floors of the aisles and galleries. These are in turn roofed
by both skillion and king post trusses.
Unlike Brunelleschi's masonry dome for
Florence's cathedral of Santa Marie del Fiore, Reed's dome
is not a true compression dome. Like St Paul's Cathedral in
London, it includes an inner suspended ceiling and an outer
dome skin that are supported from a simpler internal
structure. In the Melbourne building, eight large bowstring
trusses are fixed to a post at the top and tied together at
their base with a circular timber tension ring. To achieve
the curved shape of the dome ribs externally, the top chords
of the truss were constructed from three layers of sawn
Oregon boards laminated together to form a segmented curve.
The straight bottom chord of these trusses run either side
of the webs in two full length pieces, each 19.7m long. The
inner dome is suspended from these trusses and comprises
curved primary ceiling rafters, purlins, battens and a board
lined ceiling.
It is clear that the architects intended
to create a grandeur in the nave and transepts with the
light timber arches of the roof structure echoing and
accentuating the large contiguous arches of the dome
supports. However, their attempt to leave the space below
the arches clear of obstruction appears to have quickly come
undone. The trussed arches of the nave and transept were not
originally tied and their design relied on the bolted truss
joints of the members to resist spreading. This proved
inadequate and movement in the base of the arches forced the
top of the supporting columns to spread. To limit this, the
bottom of the arches were tied with steel pipe some time
between the international exhibitions of 1880 and
1888.
A Strategy for Design with
Timber
Economy
The architects, Reed and Barnes,
won the design competition for this building by proposing a
highly economic solution to the strict budgetary conditions
imposed on this project. The scheme proposed a predominantly
timber structure for the bulk of the building and relegated
relatively expensive masonry construction to the exterior
walls.
Timber construction was lighter, faster,
required smaller foundations and therefore reduced overall
cost in comparison to other construction methods. It is
interesting to note that when the supporting structure for
the dome was changed from timber to masonry after contracts
were let, the construction cost for the building rose by
more than 10% of the original contract sum. The imported
Oregon was only dressed where it would be touched.
Otherwise, the structure was left rough sawn and members and
linings were painted. In this way each layer of structure
had a predetermined finish in the design and therefore a
part in the painted scheme or interior decoration of the
building. To control cost, a hierarchy of detailing was
established in the building.
Timber Technology and Seasoning
When the Exhibition building was
constructed, the predominate timber engineering technology
used in Australia was from England and used mortice and
tenon joints in many of its connections. While adequate in
compression, mortice & tenon joints make poor tension
joints and most had to be strapped with steel. Members also
had to be oversized as their strength was reduced by the
formation of the mortice.
The majority of timber in the exposed
structure of this building was imported. This is not because
the local hardwoods were not strong enough, rather there was
a limited understanding at the time of the most efficient
ways to season Australian hardwoods. Hardwood seasons very
slowly and a 75mm board may take two years to season
properly. It also tends to shrink significantly and can
twist as it dries. Although timber was the structural
solution of the time, the potential use of locally sourced
timber remained unexplored while the use of imported
technology and materials dominated practice. In turn, this
lead to the acceptance of a particular aesthetic for timber
buildings in later Australian practice. Drawing from rural
and industrial buildings of early Australia and featuring
elements such as king and queen post trusses, this was
adopted in varying degrees and romanticized during the
1960's in buildings such as Tocal College, designed by
Philip Cox and Ian McKay.
Longevity
Durability and Maintenance -
Although over one hundred years old, the timber structure of
the Exhibition Building continues to perform adequately.
Besides the additional tie rods, the only timbers that have
recently required repair work are the timber base plates of
the dome where flashings and gutters deteriorated and water
penetrated the structure. This has caused decay in the
timber joints.
Moisture penetration is the most common
cause of deterioration in buildings. All buildings require
active maintenance regimes to ensure that the breakdown of
flashings and roofing, changes in ground level and damage to
downpipes and the external fabric of the building do not
compromise the internal structure. This particularly applies
to timber buildings, especially those of this age, where any
breakdown in the external fabric can result in the members
being continually wet. This leads to decay.
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