The worldwide longest arch constructed of

shawlaskewvilleUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

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1

The worldwide longest arch constructed of

concrete
-
filled steel tube

Zhang Zuo
-
an, Liu Shilin,
Juhani Virola,
Ding Dajun


Chongqi
ng Wushan Bridge (Fig.1) is a concrete filled steel tube (CFST) arch
bridge over Yangtze River. It is a half
-
through
structure with main span of 460m and height from
springing to crown of 130m or so (Fig.2), the ratio of clear rise to span is 1/3.8.
Wushan

Bridge is much larger than the original worldwide record, Guangzhu Yajisha
Arch Bridge of the same type, completed in 2000 with
main span of 360m. In the latter, the arch chord adopted
firstly 6
φ

(steel tubes) arranged in 2 rows in each arch rib,
there ar
e 6
φ
750 steel tubes, the thickness of middle 2 is 20mm and that of side 4 is
18mm. In Wushan Bridge, 4
φ
1220 tubes are used, 2 in top row and 2 in bottom, the
thickness of 2 tubes in

upper and

lower chord
s

is 22mm
,

but the thickness of lower
chord tubes in
2 segments near springing with length of 40.899m is increased to
25mm;

the width of arch ribs is 4.14m. The chord tubes through transverse tube

of

φ
711×16mm and vertical tube of
φ
610×12mm
a
re connected into CFST truss. A half
of this truss along longitudin
al was divided into 11 segments

(Fig.3)

and along
transverse into 2 ribs closed to upper and lower reaches,
between ribs, there are 20 pieces of transverse bracing, so
in whole bridge there are 64 segments, the design weight
of the max. hung segment is 118
t. The installation of segments was conducted by
using cable crane without using supports, after hanging to position, then the segments
were spliced in hanging state with tube
-
and coupler.

The cable crane system has several characteristics, such as large cable span of
576m, large weight of hoisted segment (including construction equipments 126t,
designed hoisting weight 170t), large height of cable tower of 150.22m, large hoisting
h
eight of 260m, etc. as shown in Fig.4. Fig.5 shows the hositing tower and fixed
tower.

The device for supporting cables was
firstly developed and successful to

be used in
practice, so gained national patent with No.
03234487. Fig.6 shows the construction sketch
of the device for supporting cables.

Fig.7 shows the setting of tension end of
anchorage system. Fig.8 shows
the tension of cables. Fig.9 shows
uniformly stressed distribution system of main cables at
hoisting points.

Between web chords, the cross bracings
are
set near
-
by hangers to strengthen the transverse
connection of arch ribs.

Fig.1 Completed CFST Arch Bridge

Fig.2 Sketch of general

l
ayout of Wushan Bridge

Fig.3 Division of segments


in half of arch

Fig.4 Layout of hositing and fixed
system in construction of Wusha
n Bridge

Fig.5 Hoisting tower & fixed tower

Fig.6 Construction sketch of the device
for supporting cables

Fig.7 Setting of tension
end of anchorage system

Fig.8 Tension of cables

Fig.9 Uniformly stressed distribution
syste
m of main cables at hositing points


2

Into the main tubes, into the vertical web members at the connection of arch ribs
and deck, into the transversely connecting tubes of
φ
1220×22mm above the vertical
columns and in
to the upper and lower transversely connecting tubes of
φ
711×16mm
at hangers were all injected highstrength concrete C60 developed, possessing many
working properties such as extra
-
plasticity, shrinkage
-
compensation, delay initial
setting and high
-
early
-
st
rength, etc., the 28
-
day average compressive strength of the
specimens was 79.3MPa with standard deviation of 3.5MPa. The quality after practice
met the requirements of design and code, so it is successful.

Th
e concrete injected into the main tubes of each arch rib amounted
approximately to 600m
3
, adopted continuously construction method divided in 3
segments along two banks from springing to crown. The sequence of injection was:


into the upper chord of rib towards lower river near lower reaches;


into the
upper chord towards upper river near upper reaches;


into the lower chord towards
upper river near lower reaches;


into the low
er chord towards lower river near
upper reaches;


into the upper chord toward upper river near lower reaches;


into the upper chord towards lower river near upper reaches;


into the lower chord
towards lower
river near lower reaches;


into the lower chord towards upper river
near upper reaches. Then to inject concrete into the vertical web member tubes and
into transverse connecting tubes.

Fig.10 shows bottom view of completed Wushan
Bridge. Fig.11 shows the local part of top of view. Fig.12
shows closing of arch (before retaining water of
Three
-
Gorge).

Fig.13 shows celebrating the completion of
Wushan Bridge to shoot off fireworks at night.

For the steel tubes of Wushan Yangtze River,
the hot spraying of aluminum alloy with arc was selected as long
-
acting preservative
coating, the life o
f which is considered for more than 30 years. The design of coating
is given as follows:

(1)

base
treat
ments: reaching Sa
a

roughness R
2
40
-
80
μ
m
;

(2)

spraying aluminum
-
magnesium alloy with thickness
160±25
μ
m
;

(3)

spraying sealing bottom paint of epoxy with thickness of
30
μ
m
;

(4)

spraying medium paint of micaceous iron oxide epoxy with dry membrane
thickness of 50
μ
m
;

(5)

spraying surface paint of acrylic polyurethane with dry membrane thickness
of 80
μ
m
, among which the 40
μ
m

was conducted in factory and the other
40
μ
m

was construc
ted in site after the completion of bridge.

(1)~(4) in the above design were also finished in factory.

This Bridge was completed and opened on Jan.8, 2005.





Fig.10 Bottom view of

completed Wushan Bridge

Fig.12 Closing of arch (before retaining
water of Three
-
Gorge Reservoir)

Fig.11 The local part of top of view

Fig.13 Celebrating the completion
of
Wushan Bridge


3










Fig.1


Fig.2


Fig.3



4




Fig.5 Hositing tower & fixed tower




HA


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fi硥搠慮捨潲慧攻 HT


h潳oti湧n t潷敲; FT


fi硥搠t潷敲; FFC


f潲m慬⁦i硩湧⁣慢n攻 呆C


t敭灯p慲y⁦i硩湧⁣慢n攻 D匠


摩獣桡h来⁳tri瀻 卌


獰si湧敶敬


S坌


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-
G潲来gR敳敲v潩r;⁍ L


m敡e畲敤⁷慴敲敶敬

Fi朮g


(戩⁉湳n慬l慴i潮o⁦i硥搠x潷敲


(a) Photo hoisting tower on fixed one


5






BC


扥慲i湧n捡扬敳; CL


捵c
li湥n潦 異灥u & l潷敲 灡pt 潦 摥di捥cf潲 獵灰潲ti湧
捡扬敳; UW


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l潷敲 w桥敬 潦 b敡ei湧n捡扬敳;



獴敥e⁤潷敬;⁕W


異灥u⁷桥敬 慩渠捡扬攻 UWP


異灥p⁷慬l⁰ 慴攠ef
摥di捥c f潲 獵灰潲ti湧n 捡扬敳; C坒W


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ir攠r潰攻 呗T


tr慣aive
(桯獩ti湧n wir攠r潰攻 LWP


l潷敲 w慬l 灬慴攠潦 摥di捥cf潲 獵灰潲ti湧nc慢a敳; HWR


桯獩ti湧⁷ir攠e潰敳

Fi朮g


Fi朮g


Fi朮g


6







Fig.9


Fig.10


Fig.11


Fig.12


Fig.13