a

m

38

ser

par

pre

con

the

17

com

is

the

not

in

resting

box

operat

BNE

This

of

Thai

line

five

major in

is

joints

Pontchar

in

monolithi

months,

details

of

largest

still

a

caps

of

years

design-

JOURNAL

the

intercon

precast

long

12

solution

is

The

cast

discusses 44

Lake

dry

prestressed

pile

Louisiana, consists

in

the

the

the

The

Expressway

PCI

all

role

the

and

prestressed

on

miles).

form

after

With

composed

1956,

using

slah,

time.

the

transportation

with

Causeway

design

in

Orleans,

Thailand,

(34 will

Site

gives

Authority

all-precast

the

expressways

bridge, Today,

deck

by

major

area.

constructed

supported

on

sections

at

a

An

superstructure

the New

of

a

The

km

extended

and

presents

piles.

the

was

BNE

place

were

represents

The

in

near

long.

it

completed

an

construction.

Transit

55 Pontchartrain

of concrete

all-precast,

in

fabricated

play

supporting

of

Bangkok,

girders

Bangkok cylinder

system

of

also miles)

Note:

Lake

link method.

to

Conceived

were

article

(ETA),

in

precast

The

accomplishment

The

project,

Rapid structure,

the

causeway,

girders

Thailand.

ft)

(23.8

satisfactorily.

hollow

but

features

ing

vice,

(56

cally.

allel on

the

ponents stressing

major

crete

km

train

greater Editor’s

This

land nected

and

element

Bun.

length

out. in

span-by-span

expected

World’s

world,

in

important

on

$1

total

en

the

the

the

design also

post-tensioned

is (see

long

Southeast

BNE

Expressway

Chon

used

a

Book

in

its

an is

carried

under

the

eastern

tendons.

size

new

of

of

built

the

the

Na

(BNE)

and

and

Largest

for

in

has

the

States

earned

the

and

miles)

ever

bridge

ever

city

project

Pontchartrain,

segmental,

Guinness

RECORD

(34

Bang

job

has

record,

from

the

2000,

provides

length

operation.

bridge

techniques

the

This highway

United

to

the

km

describes

Bangkok longest

in

Lake

expressway

Expressway

1).

longitudinal

match-cast

55

the

into

development

the

billion

precast

Na

operation

and

stretches

in

January

as

precasting

Fig.

Thailand,

superstructure

longest

project

$1

at-grade

breaking

of

entry

use

Bangkok

were

around

crossing

surpasses

elevated

Bang

billion,

an

precasting

contract,

In

(see

WORLD

of

the

to

external for

new

length,

construction

of

largest

the

Records

The

top edge

tire

footnote).

Louisiana,

taken. bridge

project

As

world

of the

right

the

of Bangkok,

was

build

and

The

commercial

concrete

system girders

only

precasting gigantic

Operation

NEW

Thailand

Expressway,

Ing. Bridge

-

Dr.

Sciences

Na

Bauaktiengesellschaft

Ing. Manager

-

Division

Applied

Brockmann,

Germany

Berger

of

Project

Thailand

+

Dip!.

Germany Rogenhofer,

-

BBCD

International

Bilfinger

Horst

Wiesbaden,

26

Bangkok,

Formerly,

Bremen,

University

Prof.

Christian iv

Precasting

Longest Bangkok, Bang V.. a

V , •. —— a V VV ‘V • — a 1L—zz—z:

,—

Fig. 1. Overview of the BNE project in Bangkok, Thailand, completed in January 2000. project, ETA intends to facilitate the and intersections for a total deck area In essence, this was a lump-sum de industrial development of Southeast of 1,900,000 2m (20,400,000 sq ft). sign-build contract for the turnkey Bangkok and to connect the planned The agreement stipulated the project completion of the project. Thus, the Second International Airport as well would be completed within 3’/2 years. start of construction had to overlap the as to connect the deep-water harbor The BNE contract was broken down ongoing design. In addition, Joint with the city. Another reason for the into eight phases with each phase hav Venture BBCD, under the contract, expressway is to alleviate traffic con ing a specific completion date. The had to finance the project until com gestion in and around Bangkok. reason for this requirement is that the pletion. The total cost of planning, de The purpose of this article is to pre expressway is a toll facility and, there signing, constructing.and financing the sent the design-build contract, de fore, there was a financial incentive in project was approximately $1 billion. scribe the design features of the meeting the schedule so that each bridge, discuss the construction tech completed section could be opened to DESIGN FEATURES niques used in the project, and give traffic and start collecting toll fees. the details of the precasting operation. The entire project was stipulated to be OF PROJECT completed by January 2000. The BNE was constructed through Because of the extremely short con out its DESIGN-BUILD CONTRACT entire length on top of the cen struction period, the design phase had ter and outside medians of the exist In June 1995, a contract was signed to be completed quickly. This included ing at-grade Highway 34 (see Fig. 2), between ETA and Joint Venture soil investigations and foundation de where by contract the traffic must BBCD under the sponsorship of Bilfin sign, bridge alignment and geometry, flow without interruption at a speed ger + Berger with Ch. Kamchang PLC structural design of the columns and of 80 km/h (50 miles per hour). The as the important local partner. The superstructure, preparation of shop Department of Highways is currently contract covered 55 km (34 miles) of drawings, lighting, traffic control, and upgrading Highway 34 and the two elevated expressway together with an toll facilities. Also, a very large pre projects had to be carried out simulta additional 40 km (25 miles) of ramps casting yard had to be established. neously over the same route. IV

January-February 2000 27

at

is

of

in

85

26 el

all

the

ft)

the

H-

the

tips

ex

and box

(43

suc

box

cell

box

pre

box

box each

aes

large

struc

over

estab

as

portal

above

ramps

below

of

the

which

facili

m

which

traffic at

(89

six

accom

the

The road

lanes

the

surveil

tips

average

the

external

when

the

JOURNAL

below.

The

wing

to

the

diagonal

booths

m

to

is

13 Widening

structures

wide Each

segmental

but

accommo

of

symmetri

ramps,

allows

one

to

wide

single

unique

on

for

span

from

longitudinal toll

PCI

by

27

three

to

the

construction

and multiple U-turn

a

Up

a

wing

toll was

36

were approximately

ramps,

enhance

a

single-column ft)

two

with

to

approach

at

unusually

clearance

columns

width

plaza

lead

segmental

webs.

of

frontage

of

bridge.

is 12

long

to below.

The

10 the

approximately

space

a

roadway

cast

with

has

precast

has

located

project,

Adding

have

highway

using

at (262

to

conceived is

the

and

the

toll

ramps.

the

This

and

spanning project

the

centerline

interchanges.

on

structure

webs)

elevated

ingredient

tendons

the

m

are

This

by

similar

to up

between

joints.

precast

the

supported

addition

was

weighs

match exceptionally

of

a

in

the

there

elevated pairs structure

80

highway

structure bents

highway

line

connected

BNE

H-shaped

ft)

two

superstructure.

ft).

span-by-span

Section.

tons).

on

in

dry for

girder including

major

comprised

in

existing

by

in

roadways

support

between

viaduct.

the

are

elevated

that

ramps

the

connected

This

the

were spanning

are

bridge

is

The

expressway

(94

expressway

frames.

(46

each, facilities.

essential

main

which

main

box support

to

(138 about

only

had

the

box

These

of

accelerationldeceleration

supported

into

segment exits

construction

slab

included

existing

new

existing

m

wide

m

aesthetics.

the

An

Two

build

the

Note

The

The

The

14 and cess

widening portal

modated

lance increase girders

are the

end.

over

tures

the

construction

supported

girders the

accomplished frames

of

date

cally the

lead evated

elevated, pressway

typical

cast

(i.e., struts tonnes

girder top

girder.

ft) lanes

shape

all

wide tate

bents.

support 42

girders to thetics

post-tensioning

segmental place

to

so

any

box

spe

pric

influ

maxi

to

precast

the

a

The

and

attractive

girder

of

use

has

ft).

highly

the

aesthetically

to

box

is

superior

an

(146

design

the

was

which

Also,

all

line

m

for

3),

construction,

time,

then,

44.4

slender

of

main

were

Fig.

of

the

the

same

structure.

units

provides

speed

(see

by

of

span

method.

the

solution,

of

At

shape cific

girder mum

enced

ing other pleasing

ments, lution

ft).

seg seg

Pro

deck

com

more

(146

of

a

m

bidding

that

segmental

economical

BBCD

and

coordination

44.40

alternate.

hauling

JV

of

provided

more

precast

apparent

the

a

cast-in-place

first

and

projects.

span

and

planning

the

project,

with

line

two

became

the

I-beam

the

faster

It

than

handling

the

facilitated

construction

of

Main

an

alternate

3.

During

Fig.

28

solution

slab solution.

mental efficient, duction,

between pared

BBCD phases lishment of an efficient precasting Typically, 16 piles are necessary to The difficulties in driving the piles yard, which became the largest plant transfer the loads from the main line were due to the very soft consistency ever assembled in the world. A total columns into the sand layer. In order of the upper clay layer [12 to 20 m (39 of 40,000 segments, of varying pro to produce the spun piles, a special to 66 ft) in thickness] which does not portions, were fabricated. The quan plant had to be built with sufficient ca provide any horizontal support for the tity and rate of production for box pacity to manufacture the 900,000 m piles. The heaving pressure of the co girders was one of the highest ever (2,953,000 ft) of piles required for the hesive soil during pile driving can achieved. Approximately 60 percent project. cause a displacement of more than 1 m of the overall concrete requirements for the project were used in the yard for the segments which were cast in carefully planned and always repeti tive sequences in order to increase the speed of fabrication and quality of I product. More details on the precast ing operation will be given later on in driven piles this article. 0800mm The technology of precast segmen soft clay prestressed tal construction, and particularly span- concrete by-span construction, was pioneered by Jean Muller and the firm he heads, Jean Muller International. Segmental welded joint construction with external post-ten sioning and dry joints has been imple hard ólaS, /. 30rn mented especially by Bilfinger + Berger, Germany, on many bridge projects in Southeast Asia, Africa and Australia. The principles used on the

BNE project have been achieved be I I fore but never on such a gigantic scale. For more information on seg sand, bearing stratum mental construction and on this pro ject, see Refs. 1 to 7.

CONSTRUCTION Fig. 4. Pile foundation. TECHNIQUES This section describes the various structural elements and techniques used in constructing the substructure and superstructure of the elevated bridge.

Foundation of Main Line The city of Bangkok is situated in the delta of the Menam Chao Phraya River. The underlying soil can be sim ply classified as a three-layer model, namely, soft clay, stiff clay, and sand. It was, therefore, necessary to transfer all loads to the sand layer. For the BNE project, 800 mm (31.5 in.) diameter precast spun piles, with a wall thickness of 120 mm (4.72 in.), were used. The piles are in general 30 m (98 ft) long. They are composed of two sections which are welded to gether to ensure the transfer of tension and compression forces (see Fig. 4). Fig. 5. Mainlinecolumn with superstructure.

January-February 2000 29 __H’

(3.3 ft). Thus, the speed of construc tion was often impeded by soil pro H—var. —. 27,20 files comprising five to seven intermit tent layers of clay and sand. The loads transmitted by the columns are transferred to the piles through a pile cap of 2.5 m (8.2 ft) thickness. The top of these pile caps is always below the flow line of the drainage in the center and outer medi ans of Highway 34.

Main Columns The main line columns are H- shaped and display a slender light ap pearance. The H widens from its base 27,00 m at the pile cap to the top so that the outside corners are gracefully curved Fig.6. Configuration of portals. (see Fig. 5). The architectural design also serves a structural function. The columns are located in the open drainage area of the center me dian of Highway 34 and reduce the section of this free flow channel by a minimum amount. In the erection of the superstructure, an underslung girder is used which moves through the upper arms of the column. Since there is no cross-beam, the launching is simplified. The superstructure is placed on in clined elastomeric bearings in order to avoid moments from load transfer be tween the box girder and columns under symmetrical loads. This re quires very tight construction toler ances because the planes of the bear ings must be exactly parallel to the precast segments. The average height of the main columns is 16 m (52.5 ft). The columns are cast in three parts, i.e., legs, struts, and arms. First, a kicker is cast to ad just for the differences in height be tween the varying top levels of the pile caps and the variable height of the su perstructure. This allows the use of standardized formwork to fabricate the columns. Because the tangent at the foot of the column is vertical, the joint is easily handled. The sequence of fabrication is to first erect the inner dome of the col umn formwork and then to place the prefabricated reinforcing bar cages for the legs. After the outside forms have been erected, the legs can be cast. The casting of the strut and upper arms fol lows the same procedure. Fig.7. Erectionsequence for portal segments.

30 PCI JOURNAL Portal Beams picked up by a winch and taken to D6 Segments their final location. Erection is, In areas where the main line is there The D6 segments are the main part fore, completely separated widened, i.e., at the toll plazas and the from traffic of the structure. They span in the flow. Fig. 7 shows the erection proce merging areas of the ramps, it is nec transverse direction with a width of dure for portal segments. essary to place the superstructure on 27.20 m (89 ft) over six lanes of traf portal beams because the same cross- fic. For typical segments, their height section of Highway 34 must be main D2/D3 Segments and length are 2.60 and 2.55 m (8.53 tained. A total of 180 portals were D2 and D3 segments for two- or and 8.37 ft), respectively; for pier seg erected. three-lane decks are used for the ments, their width is 1.775 m (5.82 The portal beams are rigidly fixed at ramps, interchanges, and toll plazas. ft). The weights of typical girder and the main line portal column and at These types of segments have been pier segments are 85 and 100 tonnes each end connected to the outside previously used successfully on other (94 and 110 tons), respectively. The columns by a hinge. The maximum expressway projects by Bilfinger + unusually slender cross-section has span is typically 27 m (89 ft) long. Berger in Bangkok. Both are box gird inclined webs and two struts in the The beams are formed by match-cast ers with a deck having a maximum middle of the segment (see Fig. 9). box girders with vertical webs, which variable width of 15.60 m (51.2 ft) The inclination of the webs accentu are externally post-tensioned. (see Fig. 8). ates the curvature of the outside of the The portal columns have the same Note that these segments are erected columns and carries this line to the form as the H-columns but have, in with an overhead truss girder, which is horizontal plane of the deck. addition, corbels with the same cross- launched from column to column. The spans are longitudinally pre section as the portal beams. A cast-in- First, the segments are hung from the stressed by 22 tendons. Twenty of place joint is necessary to provide for truss and properly aligned. They are these tendons are placed externally in the adjustment between these corbels then post-tensioned longitudinally by the box and two are placed internally and the first match-cast segment. The external tendons in the box, and fi in the edge beam. The transverse post- rigid connection and the resulting ten nally placed on the bearings. tensioning is accomplished not only sile forces in this area are not only pre-compressed by the external ten dons in the beam but also by internal fl lflflf) - 1Rfl tendons in the upper part of the col D2: 7,00-11,9Cm umn (see Fig. 6). The portal beams span three traffic 0,20 m lanes in each direction and it was not permitted to interrupt the traffic for construction operations. The conven 2,40 m tional method of using beams cast-in- place on lower formwork was in addi tion too slow considering the tight D 3: 5,50 m time constraints. To fulfill both de — I mands, it was decided to use precast D2: 3,7Cm components that could be erected with metric dimensions an overhead truss. This portal truss has two compo Fig. 8. Configuration of D2/D3 segments. nents, namely, a launching girder with a length of approximately two main line spans and an erection girder, two portal spans long. Both components 27,20 are connected by a turntable, which is placed on one column. The complete truss is first launched one span between the arms of the H- column, and then vertically and hori precast strut zontally supported on three columns. Then, the turntable is fixed on the por tal frame. Finally, the erection girder is turned by 90 degrees and is then supported at the ends by the outside portal columns. metric dimensions The portal segments are delivered to the center median where they are Fig. 9. Configuration of D6 segments.

January-February 2000 31 ____

deviator segment A

deviator segment B

tendons

E pier segment anchorages

Fig. 10. Longitudinal post-tensioning. by the tendons in the top slab, but also The upper flanges of the launching place of erection. The chassis are by placing them in the webs and bot girder form the planes on which the equipped with hydraulic jacks, which tom slab (see Figs. 10 and 11). chassis move. The swivel crane places allow for three-dimensional adjust The H-column, the underslung truss, each segment on one of these chassis, ments, i.e., vertical, horizontal, and ro and the D6 segments of the superstruc which is then pulled by a winch to the tational movements. After adjusting ture were designed by Jean Muller In ternational as an integrated approach to the construction of the elevated main bridge line structure. The cross-beam of the deck H-column forms the support for the launching girder and the arms provide the horizontal support. The cross-sec ‘N live/ end dead end tion of the girder is V-shaped and it is equipped with a swivel crane for lifting and placing the segments. The segments are placed on chassis (frame supports), which are equipped with hydraulic jacks for adjusting and dead end leveling the span. The length of the girder is slightly longer than the maximum of two spans. It comprises a load carrying plate girder in the front and a truss to cantilevers and box girder support the launching in the rear. The swivel crane can be placed either at the nose of the plate girder or on the last erected span. It is, therefore, pos Z sible to deliver the segment to a 1 sta tion below the swivel crane at grade as tendon well as to the already erected deck (see Fig. 12). Fig. 11. Transverse post-tensioning.

32 PCI JOURNAL ,Jill Fig. 12. Underslung erection girder.

all the segments of a span, the external Table 1. Comparison of material quantities in superstructure segments. tendons are placed in the box and Quantities per square meter Segment Segment stressed. Then, the girder is lowered to of bridge deck 2xD3 D6 transfer the load to the bearings. The girder is supported by three slid Concrete, 3m 0.51 0.49 ing chairs and two temporary chairs Reinforcing bars, kg that are required for launching. It is 70.6 59.2 launched by the front chassis that is Post-tensioning tendons, kg 24.4 24.0 motorized. This chassis needed for Conversionfactors: 12m = 10.76sq ft; 1 3m = 35.3cu ft; 1kg = 2.2 lbs. launching is fixed to the erected super structure and pushes the girder forward using a gear. For longer spans, the cen ter of gravity during launching is in Table 2. Quantities of components/materials in total structure. front of the last support. A reaction Components/Materials Quantity force is transferred through the truss and into the erected deck. Deck area. 2m 1,900,000 D6 deck area, 2m 1,400,000 D2/D3 deck area, 2m 500,000 Comparison of D2/D3 with D6 Segments D6 segments, pieces 21,320 D2/D3 segments, pieces 18,250 The contract terms of the project al lowed the bidders considerable free Mainline piers, pieces 1,255 dom in bidding for the design. Bilfinger + Berger elected to use D2/D3 seg Piles, pieces 28,882 ments for the ramps with a width vary ing from 6.0 to 10.75 m (20 to 35 ft). Concrete, 3m 1,800,000 For the 55 km (34 miles) mainline, they selected the D6 segments. Almost Reinforcing bars, tonnes 167,000 80 percent of the total deck area of 1,900,000 2m (20,400,000 sq ft) is Post-tensioning tendons, tonnes 52,240 formed by D6 segments. A comparison Conversionfactors: I 2m = 10.76sq ft; 1 3m = 35.3cu ft; I tonne = 1.10tons.

January-February2000 33 of the main material quantities of D3 At the same time, all the logistics, i.e., the cost of land, equipment, and trans and D6 segments is shown in Table 1. production, handling, hauling, and portation facilities was about $26 mil Evaluated by local prices in Bangkok, other operations are simplified. The lion. The Bang Bo precasting yard the quantity differences alone reflect a total quantities of components/materi (see Fig. 13) is the largest plant in the savings of 7 percent in the superstruc als of the project are listed in Table 2. world and boasts the highest installed ture. Of course, these savings are not production capacity of precast compo only limited to the superstructure, but nents ever achieved. THE BANG BO extend to the substructures as well. Construction of the plant began in PRECASTING YARD the summer of 1995. Within 9 months In order to construct the BNE pro after starting the yard fill, production Construction Speed and ject, a giant precasting yard had to be of the segments commenced. A total Overall Material Quantities set up to fabricate the thousands of of 40,000 bridge segments and 30,000 The biggest advantage of segmen segments required for the bridge. The other precast reinforced concrete ele tal construction with external post- Bang Bo precasting plant was con ments such as road barriers and I- tensioning and dry joints is the speed structed at Kilometer 29, about 4.5 km beams for the ramps were produced. with which the superstructure can be (2.8 miles) north of the expressway. The facility also contained workers’ erected. In bridge construction, the Comprising an area of about 650,000 camps, canteens, offices and laborato critical path (after a given starting 2m (7,000,000 sq ft), the plant was lo ries, carpentry, mechanical and weld period) always shifts to the super gistically planned down to the mm ing workshops, a central store, a rein structure. Any increase in the rate of utest detail. forcing bar cutting and bending shop, erection directly accelerates the con The marshy terrain in the delta of the plus an area for the production and as struction period. Menam Chao Phraya River, together sembly of post-tensioning ducts. For the BNE project, six overhead with access roads, had to be completely Approximately 1800 superstruc trusses (D21D3) and five underslung developed in order to efficiently pro ture segments (D2/D3, D6, and por girders (D6) were used. When all the duce and transport the heavy precast tals) were produced per month in a girders are in operation, 2500 m (8200 concrete components. The entire pro quality controlled environment. The ft) of ramps and 2100 m (6890 ft) of duction area was founded on driven re storage area for segments and other mainline deck were erected per month. inforced concrete piles and overlaid precast sections (see Fig. 14) was In square meters of deck area, the with a cast-in-place concrete slab. about 260,000 2m (2,800,000 sq ft), erection speed for D6 girders was The amount invested in constructing corresponding to a production period twice as high as for the D2/D3 trusses. the complete plant, without counting of 7 weeks.

Fig. 13. Layout of precasting yard.

34 PCI JOURNAL to

by

op

pre 200 was

each rn3fb area. were con

enor

could

at

output

reduce reduce of of

line. the used

concrete

100 segrega sections equipped vibratorS

1,100,000 and to placed to the

there

for

of

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ft) Twenty-five

concrete were

Segments were was slump

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Both to (106 reinforced

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produCtiOfl tasks. Precast fresh

the

where proportioned

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and of

an

of the

3 segment

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concrete concrete.

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D6 time cohesive heavily cu

molds, ends concrete was with

mixers logistical

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15.

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Vertical For The

Production posite mous of (3530 and cast m3 with mixing produce truck to conveyor consolidate required mm two The mixer crete highly tion Fig. JanuaryFebrUarY

to

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Fig.

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carried

the

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on

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(see

JOURNAL

segment

new

the (concrete

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drawings.

area,

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the

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the

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and

segments

post-tensioning).

geometric

checked

the

on

fully

by

y,

with

required

the

transported,

the

here,

attention

each

deformations

the

up

after-cast line.

the

x, After

the

necessary,

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typical

is

the

software

its

mold

match-cast

areas

placed

of

layout

a

of

and

intermediate different

were

were

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post-tensioning,

since

the

the on

curing,

direction.

spanning

lifted

is

between

Such

and

shifted

From

the

stiffnesses.

transverse

molds.

the

Special Unlike

Each

Span

16).

structure,

mix,

avoid

ent timing

storage verse wide cially

time-dependent by

out. duction pier

segments ments

reached

segment to work

accordance check position. ated lines.

monitor After was

Special

ometry

ment,

were crete

veyed

quired and the

joints

to

of

12

ar

re

15.

D6

bar

the

ten

ten

this bars

pre

lift

with

pre

seg

seg

day. skill

only

have

19

more

cast,

are

casting

two

ends

Fig.

of

the

one

pier

variable

addition,

longitudi

segments,

curvature

formwork

travel

in areas.

the

a

were

pulled)

they

the

special

between

In

were

achieve

ratio

the

segment.

D6

whereas deviators

from

direction,

the

technical

transverse

be

segments

at

for pattern:

reinforcing

fabrication transverse

match-casting

with

within

reinforcing

of

a

To

cages

shown

the

impart pier

pier

storage

operation,

and

the

superstructure

rails

molds. and the

a

cage

which

later

to

line,

to

segment,

to

struts,

therefore,

direction, for

are

to

bar

needed.

D21D3

typical

of

on

26 two

needed

this

storage

for

difference

days.

bar

the

position

following

one will

surveyed

production,

segments,

of

a

segments

for

and,

struts

2

are

typical

transported

area

lines

also

forms

were

of

moved

a

production

were

longitudinal

the

towers

fixing

those

cranes (through

and

segment

with

the

pier

total

also

knowledge

form

in

are

there

However,

took

a

for

transverse

the

and

Molds

were

illustrate

is

particular

the

rate

and

The

reinforcing

tendons

the

a required.

molds

molds

the

In First,

i.e., Survey Match-cast Intermediate

Reinforcing Molds

Tower

To

Typical

For

typical

1.

nal

diabolos

dons fabrication dons,

together

5. molds

3. 6. which

4.

10 are

stripped, and production In 2.

cycle ranged

a complicated casting

ment. high

38 For jigs.

ment 7,

there position,

molds

on molds

fixed.

/

to

of

in

in

to

of

to to

on

are

the

the

psi)

con

con

con

limit

were

sheet

thick

dura

using

could

33

maxi

where

as

before

hydra

appro

speci

appro

mixing

to

shifting

reduces

for

a

psi).

the

of

expedite transportation.

concrete. required.

in.)

placed

For

percent

be

high-early

molds

(2900

slab

fresh

segment

cracking.

suitable

applied

the

take of

The

a

precast

plastic and

is

for

(1

beneficial that

properties

This

To

50

the

of

molds,

serves

a

of was

not

match-casting

to superstructure

cement

(8000

temperature

required

MPa

deck

was

the

cm these

practical

to

ready

satisfactory.

strength

zero. of

a

the

the

sheet

cool

more

3

and

thermal

time,

with components

mix

20

on

found

quality

situation.

was

MPa

is

match-casting

not

surfaces

a

following

might

is

to

a to

to of

of

due

stripping

method.

is

force

temperature

this

confined.

it

55

operations,

segment

and

by

temperature

the

stationary

high

it

been

job

that

is

general,

a

plastic

temperature

At

95°F)

segment

evaporation

covered

in

another

influence

was

water

for

concrete,

hours,

concrete

strength allow

to In

air

has

minimizes

D6

way

segment

The

unformed

measures

10

segments

to

it

for

since

placing

the

of

reasons,

a

(91

concrete

were

compressive

dissipation

general,

16.

and

specific prestress

short-bed previous

produced

started.

placing

cast.

the

prevent

producing

Superstructure

All

The

In

Fig.

36

the

bulkhead

the position.

strength order of produced be

After concrete

are post-tensioning get

such tion match-casting

35°C to water. heat the

crete layer

In

mum

hardened crete,

segments one know fresh priate

the crete,

priate

bility

bleeding fied produced using the long bed method. This is because their dimensions are smaller, the spans are shorter, the ge ometry is simple, and the number of pieces is relatively limited. Here, the soffit form was laid out for a full span. The outside and inner formwork trav eled to the next position after harden ing of the last cast segment. To achieve —I a high degree of accuracy between seg i-I I ments, match-casting was also used in I — ! I-. this operation. At the end of the casting — operation, all segments of one portal - - — ! span were aligned in a row. — I Figs. 17, 18 and 19 show progressive :‘.r1 views of the project under construction.

CONCLUDING REMARKS Precast segmental, span-by-span construction using dry joints is partic ularly advantageous in serial produc tion when a limited number of struc Fig. 17. Positioning of Segment D6 on mainline column. tural elements are reproduced many times. The rate of construction is much faster than any other comparable construction method. In addition, a very high quality product is ensured. The planning of an industrialized se rial production project must encom pass all steps of the process, namely, planning of the production output, de livery of materials, production itself, storage, transportation, and erection of the segments. The required means of production form a fixed ratio. The pro duction is equivalent to increasing all parts of the operation at the same rate. Therefore, the complete planning pro cess and its adaptation to a changing environment requires special attention. The above factors fit very well within the context of Thai society and culture, as well as the country’s geo graphical configuration. This makes the BNE project, undoubtedly, one of the most interesting and challenging bridges of modem times. It is expected Fig. 18. Overview of progress in erection of bridge superstructure. that the successful completion of the BNE project will not only improve the transportation system in the Bangkok CREDITS area, but will also foster commercial growth in Southeast Thailand. Owner: Expressway and Rapid Tran - Jean Muller International, San sit Authority, Bangkok, Thailand Diego, California (Columns, Super Owner’s Engineer: Louis Berger structure) ACKNOWLEDGMENT Group, East Orange, New Jersey Contractor: Joint Venture, Bilfinger + The authors would like to thank Engineering Consultants: Berger Bauaktiengesellschaft, Wies Jack Egan of JV BBCD for reviewing - Asian Engineering Consultants, baden, Germany (Sponsor) and Ch. this paper and ensuring the accuracy Bangkok, Thailand (Alignment, Kamchang Public Company, Lim of the English language. Foundations) ited, Bangkok, Thailand

January-February 2000 37 I — .4 %_,_•_

Fig. 19. The new Bang Na Expressway was completed in January 2000. This picture was taken in December 1999. Figs. 17, 18 and 19 are published through the courtesy of Jean Muller International.

REFERENCES

1. Podolny, W., and Muller, 3., Construction and Design of Pre 5. Sofia, M., and Homsi, E., “Fabrication and Erection of Pre stressed Segmental Bridges, John Wiley, New York, NY, cast Concrete Segmental Boxes for Baldwin Bridge,” PCI 1982. JOURNAL, V. 39, No. 6, November-December 1994, pp. 36- 2. Pate, D., “The Chesapeake and Delaware Canal Bridge — De 52. sign-Construction Highlights,” PCI JOURNAL, V. 40, No. 5, 6. Roberts-Wollmann, C. L., Breen, J. E., and Kreger, M. E., September-October 1995, pp. 20-30. “Temperature Induced Deformations in Match Cast Seg 3. Shafer, G., and Brockmann, C., “Design and Construction of ments,” PCI JOURNAL, V. 40, No. 4, July-August 1995, pp. the Bang Na — Bang Ph — Bang Pakong Expressway,” Pro 62-71. ceedings, Volume 1, Fédération Internationale de la Précon 7. Borkenstein, D., Brockmann, C., and Fischer, 0., “The Bang

trainte (FTP), XIII Congress, Challenges for Concrete in the Na — Bang Ph — Bang Pakong Expressway: Design and Test Next Millennium, Amsterdam, Netherlands, May 23-29, 1998, Loading of a Precast Segmental Bridge Structure,” Taiwan pp. 275-280. Construction Research Institute (Publisher): 1999 Bridge 4. Shafer, G., “Bangkok Blockbuster,” Civil Engineering, V. 69, Construction Automation Seminar, Taipei, Taiwan, 1999, pp. No. 1, January 1999, pp. 32-35. 37-59.

38 PCI JOURNAL