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惯性矩道路与桥梁工程中英文对照外文翻译文献

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2021-01-24 16:12
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2021年1月24日发(作者:kral)



中英文对照外文翻译


(
文档含英文原文和中文翻译
)

Bridge research in Europe

A brief outline is given of the development of the European Union, together with
the research platform in Europe. The special case of post-tensioned bridges in the UK
is discussed. In order to illustrate the type of European research being undertaken, an
example
is
given
from
the
University
of
Edinburgh
portfolio:
relating
to
the
identification of voids in post-tensioned concrete bridges using digital impulse radar.

Introduction

The
challenge
in
any
research
arena
is
to
harness
the
findings
of
different
research
groups
to
identify
a
coherent
mass
of
data,
which
enables
research
and
practice
to
be
better
focused.
A
particular
challenge
exists
with
respect
to
Europe
where
language
barriers
are
inevitably
very
significant.
The
European
Community
was
formed
in
the
1960s
based
upon
a
political
will
within
continental
Europe
to
avoid the European civil wars, which developed into World War 2 from 1939 to 1945.
The strong political motivation formed the original community of which Britain was
not a member. Many of the continental countries saw Britain’s interest as being purely


economic.
The
1970s
saw
Britain
joining
what
was
then
the
European
Economic
Community
(EEC)
and
the
1990s
has
seen
the
widening
of
the
community
to
a
European
Union,
EU,
with
certain
political
goals
together
with
the
objective
of
a
common European currency.

Notwithstanding
these
financial
and
political
developments,
civil
engineering
and bridge engineering in particular have found great difficulty in forming any kind of
common
thread.
Indeed
the
educational
systems
for
University
training
are
quite
different
between
Britain
and
the
European
continental
countries.
The
formation
of
the
EU
funding
schemes

e.g.
Socrates,
Brite
Euram
and
other
programs
have
helped
significantly.
The
Socrates
scheme
is
based
upon
the
exchange
of
students
between
Universities
in
different
member
states.
The
Brite
Euram
scheme
has
involved
technical
research
grants
given
to
consortia
of
academics
and
industrial
partners within a number of the states

a Brite Euram bid would normally be led by
an industrialist.
In
terms
of
dissemination
of
knowledge,
two
quite
different
strands
appear
to
have emerged. The UK and the USA have concentrated primarily upon disseminating
basic
research
in
refereed
journal
publications:
ASCE,
ICE
and
other
journals.
Whereas
the
continental
Europeans
have
frequently
disseminated
basic
research
at
conferences where the circulation of the proceedings is restricted.
Additionally, language barriers have proved to be very difficult to break down.
In
countries
where
English
is
a
strong
second
language
there
has
been
enthusiastic
participation
in
international
conferences
based
within
continental
Europe

e.g.
Germany,
Italy,
Belgium,
The
Netherlands
and
Switzerland.
However,
countries
where English is not a strong second language have been hesitant participants }

e.g.
France.
European

research

Examples
of
research
relating
to
bridges
in
Europe
can
be
divided
into
three
types of structure:
Masonry arch bridges
Britain has the largest
stock of masonry arch bridges.
In certain
regions
of the
UK up to 60% of the road bridges are historic stone masonry arch bridges originally
constructed for horse drawn traffic. This is less common in other parts of Europe as
many of these bridges were destroyed during World War 2.
Concrete bridges


A large stock of concrete bridges was constructed during the 1950s, 1960s and
1970s. At the time, these structures were seen as maintenance free. Europe also has a
large
number
of
post-tensioned
concrete
bridges
with
steel
tendon
ducts
preventing
radar inspection. This is a particular problem in France and the UK.
Steel bridges
Steel bridges went out of fashion in the UK due to their need for maintenance as
perceived in the 1960s and 1970s. However, they have been used for long span and
rail bridges, and they are now returning to fashion for motorway widening schemes in
the UK.
Research activity in Europe

It
gives
an
indication
certain
areas
of
expertise
and
work
being
undertaken
in
Europe, but is by no means exhaustive.
In order to illustrate the type of European research being undertaken, an example
is
given
from
the
University
of
Edinburgh
portfolio.
The
example
relates
to
the
identification of voids in post-tensioned concrete bridges, using digital impulse radar.
Post
-
tensioned

concrete

rail

bridge

analysis

Ove
Arup
and
Partners
carried
out
an
inspection
and
assessment
of
the
superstructure
of
a
160
m
long
post- tensioned,
segmental
railway
bridge
in
Manchester to
determine its
load-carrying capacity
prior to
a transfer of ownership,
for use in the Metrolink light rail system..
Particular attention was paid to the integrity of its post- tensioned steel elements.
Physical inspection, non-destructive radar testing and other exploratory methods were
used to investigate for possible weaknesses in the bridge.
Since the sudden collapse of Ynys-y-Gwas Bridge in Wales, UK in 1985, there
has been concern about the long-term integrity of segmental, post- tensioned concrete
bridges
which
may
b
e
prone
to
‘brittle’
failure
without
warning.
The
corrosion
protection of the post-tensioned steel cables, where they pass through joints between
the segments, has been identified as a major factor affecting the long-term durability
and consequent strength of this type of bridge. The identification of voids in grouted
tendon
ducts
at
vulnerable
positions
is
recognized
as
an
important
step
in
the
detection of such corrosion.
Description of bridge
General arrangement
Besses o’ th’ Barn Bridge is a 160 m long,
three span, segmental, post-tensioned


concrete railway bridge built in 1969. The main span of 90 m crosses over both the
M62
motorway
and
A665
Bury
to
Prestwick
Road.
Minimum
headroom
is
5.18
m
from the A665 and the M62 is cleared by approx 12.5 m.
The superstructure consists of a central hollow trapezoidal concrete box section
6.7 m high and 4 m wide. The majority of the south and central spans are constructed
using
1.27
m
long
pre-cast
concrete
trapezoidal
box
units,
post- tensioned
together.
This
box
section
supports
the
in
site
concrete
transverse
cantilever
slabs
at
bottom
flange level, which carry the rail tracks and ballast.
The
center
and
south
span
sections
are
of
post-tensioned
construction.
These
post-tensioned sections have five types of pre-stressing:
1. Longitudinal tendons in grouted ducts within the top and bottom flanges.
2.
Longitudinal
internal
draped
tendons
located
alongside
the
webs.
These
are
deflected at internal diaphragm positions and are encased in
in site
concrete.
3.
Longitudinal
macalloy
bars
in
the
transverse
cantilever
slabs
in
the
central
span .
4. Vertical macalloy bars in the 229 mm wide webs to enhance shear capacity.
5. Transverse macalloy bars through the bottom flange to support the transverse
cantilever slabs.
Segmental construction
The pre-cast segmental system of construction used for the south and center span
sections
was
an
alternative
method
proposed
by
the
contractor.
Current
thinking
suggests
that
such
a
form
of
construction
can
lead
to
‘brittle’
failure
of
the
ent
ire
structure without warning due to corrosion of tendons across a construction joint

The
original design concept had been for
in site
concrete construction.
Inspection and assessment
Inspection
Inspection work was undertaken in a number of phases and was linked with the
testing required for the structure. The initial inspections recorded a number of visible
problems including:
Defective waterproofing on the exposed surface of the top flange.
Water trapped in the internal space of the hollow box with depths up to 300 mm.
Various drainage problems at joints and abutments.
Longitudinal cracking of the exposed soffit of the central span.
Longitudinal cracking on sides of the top flange of the pre-stressed sections.


Widespread
sapling
on
some
in
site
concrete
surfaces
with
exposed
rusting
reinforcement.
Assessment
The subject of an earlier paper, the objectives of the assessment were:
Estimate the present load-carrying capacity.
Identify any structural deficiencies in the original design.
Determine reasons for existing problems identified by the inspection.
Conclusion to the inspection and assessment
Following
the
inspection
and
the
analytical
assessment
one
major
element
of
doubt still existed. This concerned the condition of the embedded pre-stressing wires,
strands, cables or bars. For the purpose of structural analysis these elements

had been
assumed to be sound. However, due to the very high forces involved,

a risk to the
structure, caused by corrosion to these primary elements, was identified.

The initial recommendations which completed the first phase of the assessment
were:
1.
Carry
out
detailed
material
testing
to
determine
the
condition
of
hidden
structural elements, in particular
the grouted post-tensioned steel cables.
2. Conduct concrete durability tests.
3. Undertake repairs to defective waterproofing and surface defects in concrete.
Testing procedures
Non-destructi
v
e radar testing
During the first phase investigation at a joint between pre-cast deck segments the
observation of a void in a post-tensioned cable duct gave rise to serious concern about
corrosion and the integrity of the pre-stress. However, the extent of this problem was
extremely difficult to determine. The bridge contains 93 joints with an average of 24
cables
passing
through
each
joint,
i.e.
there
were
approx.
2200
positions
where
investigations could be carried out. A typical section through such a joint is that the
24 draped tendons within the spine did not
give rise to concern because these were
protected by
in site
concrete poured without joints after the cables had been stressed.
As
it
was
clearly
impractical
to
consider
physically
exposing
all
tendon/joint
intersections,
radar
was
used
to
investigate
a
large
numbers
of
tendons
and
hence
locate duct voids within a modest timescale. It was fortunate that the corrugated steel
ducts
around
the
tendons
were
discontinuous
through
the
joints
which
allowed
the


radar to detect the tendons and voids. The problem, however, was still highly complex
due to
the high density
of other steel
elements which could
interfere with
the radar
signals and the fact that the area of interest was at most 102 mm wide and embedded
between 150 mm and 800 mm deep in thick concrete slabs.
Trial radar investigations.

Three companies were invited to visit the bridge and conduct a trial investigation.
One
company
decided
not
to
proceed.
The
remaining
two
were
given
2
weeks
to
mobilize,
test
and
report.
Their
results
were
then
compared
with
physical
explorations.
To make the comparisons, observation holes were drilled vertically downwards
into the ducts at a selection of 10 locations which included several where voids were
predicted and several where the ducts were predicted to be fully grouted. A 25-mm
diameter
hole
was
required
in
order
to
facilitate
use
of
the
chosen
horoscope.
The
results from the University of Edinburgh yielded an accuracy of around 60%.
Main radar sur
v
ey, horoscope verification of
v
oids
.

Having
completed
a
radar
survey
of
the
total
structure,
a
baroscopic
was
then
used to investigate all predicted voids and in more than 60% of cases this gave a clear
confirmation
of
the
radar
findings.
In
several
other
cases
some
evidence
of
honeycombing in the
in site
stitch concrete above the duct was found.

When
viewing
voids
through
the
baroscopic,
however,
it
proved
impossible
to
determine their actual size or how far they extended along the tendon ducts although
they
only
appeared
to
occupy
less
than
the
top
25%
of
the
duct
diameter.
Most
of
these voids, in fact, were smaller than the diameter of the flexible
baroscopic being
used (approximately 9 mm) and were seen between the horizontal top surface of the
grout
and
the
curved
upper
limit
of
the
duct.
In
a
very
few
cases
the
tops
of
the
pre- stressing
strands
were
visible
above
the
grout
but
no sign
of
any
trapped
water
was seen. It was not possible, using the baroscopic, to see whether those cables were
corroded.
Digital radar testing
The test method involved exciting the joints using radio frequency radar antenna:
1 GHz, 900 MHz and 500 MHz. The highest frequency gives the highest resolution
but
has
shallow
depth
penetration
in
the
concrete.
The
lowest
frequency
gives
the
greatest depth penetration but yields lower resolution.
The data collected on the radar sweeps were recorded on a GSSI SIR System 10.

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