Construction and Civil Contracting
specialist
bridge
construction
warramboo
bridge , mesa a
mine site in
western
australia
specialist
bridge
construction
From the bold impact of cable-stayed designs to the
timeless grace of slender concrete arches, bridges are
among the pinnacles of man’s structural achievements.
SRG has been designing, constructing,
repairing and strengthening bridges
since the 1960’s becoming an
acknowledged leader in bridge works
on an international level. SRG have
completed projects throughout
Australia, South East Asia, the Middle
East, the United Kingdom and Africa.
As part of the BBR Global Network of
Experts, SRG utilises the most advance
technology available.
INCREMENTAL LAUNCHED
BRIDGES
The incremental launching method
was developed in the early 1960’s for
concrete structures. It combines the
advantages of pre-cast segmental
construction with those of segmental
cast insitu methods.
The deck is cast in segments behind an
abutment under controlled conditions.
High concrete quality and precise
dimensions are assured. Reinforcement
crosses each joint in addition to the
bonded post-tensioning tendons as
each new segment is cast directly
against the already cured one ahead
of it. The concentric pre-stress
required during launching guarantees,
in addition, an excellent, relatively
maintenance-free performance of the
bridge during its entire lifetime. By
avoiding costly and time consuming
false work and by concentrating all
construction activities in the small
fabrication area, considerable savings
in cost and time against conventional
bridge construction are achieved. This
has been demonstrated all over the
world.
CABLE STAY BRIDGES
Cable-stayed bridges have the ability
to meet the increasing demand for
long span structures. Since 1950
this bridge construction method has
become a popular choice around the
world. Their advantages lie mainly in
their elegance, increased aerodynamic
stability, reduced costs for abutments
and faster, easier construction,
delivering a light weight structure.
SRG can provide strand (BBRHiAm
ConaTM), wire (DinaTM / HiAmTM) or
bar type stay cables for this specialist
method of bridge construction which
is especially suitable for medium
to long span bridges from 100m to
1,000m. Technical, appearance and
economical factors suit this solution.
For smaller bridges, other parameters
may drive in the choice of a cablestayed solution such as reduced depth
of deck, construction methodology
or aesthetics. For suspension bridges,
cable-stay technology can also be
incorporated for the main suspension
cables as well as for the hangers.
Cable-stayed bridge construction is
no stranger to SRG, having completed
numerous projects in Australia
including the Eleanor Schonell
Bridge in Queensland as well as
internationally.
SEGMENTAL BRIDGES
With the insitu balanced cantilever
method, the bridge superstructure is
usually built from one or more piers
by means of formwork travellers.
Normally the structure advances
from a short pier head segment
symmetrically in segments of about
3m to 5m in length to the mid span
or to an abutment, respectively (load
balancing method).
Precast segmental balanced cantilever
construction is usually undertaken
in instances where high production
rates are required or on very large
scale projects. Segment sizing is
often limited by weight and transport
dimensions, as the precast units are
often delivered by road. The segment
erection may be from a full span truss
or more localised using craneage or
lifting frames.
The post-tensioning tendons are
arranged according to the bending
moment diagram for the cantilever,
with a high concentration above
the pier, progressively moving away
from the pier the number of tendons
gradually decreases.
The use of the cantilevering
construction method, for medium
and long span concrete bridges,
is recommended especially where
scaffolding is difficult or impossible to
erect, for example over deep valleys,
wide rivers, highways or in case of
expensive foundation conditions for
scaffolds. Typically spans range from
50m to over 300m, but are most
commonly in the 80m to 250m region.
Span by span construction commonly
utilises an erection truss where the
whole span which is assembled from
precast elements, is either hung on
bars or supported from underneath
until post-tensioned and the load
transferred onto the permanent pier
bearings. This form of construction
is suited to major viaduct and
bridgeworks due to the scale of the
systems utilised. Typically segments
are up to 3.5m long, 70t, and spans
range from 30m to 50m.
With span by span construction, the
post-tensioning tendons are normally
external to the concrete and fitted in
HDPE sheathing, in a deflected profile
to economise on the post-tensioning
quantity and efficiency.
Alternative construction solutions
include whole span precast elements,
where the individual weight can be
up to 7,000t or cast in situ utilising
systems such as a movable scaffold
systems (MSS). Such solutions are
suited to extremely large infrastructure
projects. In many locations,
conventional cast-insitu solutions are
utilised, particularly in the Middle East
where SRG have an extensive portfolio
of structures built with this method.
MAINTENANCE OF BRIDGES
Bridges exist throughout the world in
various shapes and forms. All of them
require maintenance and the owners
of these bridges look for cost effective
means to upgrading or maintain them.
SRG can provide a variety of specialist
services using state of the art
technology for the maintenance or
upgrade of bridge structures including:
¢¢External
post-tensioning using
strand and bar systems
¢¢Carbon
fibre strengthening
systems, either slack applied or
post-tensioned
¢¢Bearing
replacement including
temporary works design and
jacking
¢¢Concrete
overlays and joint
replacement
about
us
We are an Australian complex services company.
We solve the challenging and difficult problems
that others can’t. Our vision is to make the
complex simple for our customers.
We have people working across Australia and the
world bringing our unique blend of innovation,
precision, technical excellence and safety to every
mining and infrastructure project we touch.
Since 1961, we have worked on many of the iconic
stadiums, skyscrapers, bridges, dams, structures
and mining projects, both here in Australia,
and overseas.
Issue 2015/07
That’s because we’re not afraid to challenge what
is considered possible.
Get to know us at srglimited.com.au
aUSTRALIA / AFRICA / MIDDLE EAST / ASIA PACIFIC / HONG KONG
SRGlimited.com.au
CALL
1300 775 477
+61 8 9267 5400