gumjae bridge - extradosed bridge parametric study

www.MidasUser.com

Extradosed Bridge Design

and Construction

Modeling, Integrated Design & Analysis Software

MIDAS Information Technology Co., Ltd.

Naga Ravi Kiran

2

Structural Engineering Seminar

http://www.MidasUser.com

Extra Dosed Bridge – A Introduction1

Contents

Gyumjae Bridge Project2

3



Introduction

Cable Stayed Bridge Extradosed Bridge

What is the difference?

4



Introduction

Cable Stayed Bridge

Tension

Compression

Extradosed Bridge

Compression

Tension

Prestress

5



Structural Behavior

Cable Stayed Bridge Extradosed Bridge

Stay cables vertically support the girder like

elastic bearings to the girder

Extradosed cables transmit longitudinal force

to the girder like post-tensioning tendons with

very large eccentricities.

6



Design Criteria for Geometry

Span by depth ratio: L/hc = 30-35

Span by tower height ratio: L/Ht = 15

Side span to main span ratio: L1/L = 0.6-0.8

Cable arrangement: Semi-fan or harp cable arrangement

7



Advantages

Suitable for spans of 100-200 m

No need for diaphragms at anchorage locations

Use of normal prestressing anchorages

No need for tendon adjustment

Smaller stress change in cables due to live loads

More compact pylons

Less changes in deck deflection during construction by Balanced Cantilever Method

Simplified construction due to Lower height of pylons.

8



Analysis Procedure

Analysis for an Extradosed bridge is done in 2 steps:

1. Preliminary analysis to find cable forces or Final Stage Analysis:

a) Full Modeling without Construction stages

b) Simple linear static analysis

c) Calculation of Unknown Load factors for Initial Cable force.

2. Design Stage Construction Analysis:

a) Full model along with the Construction stages

b) Application of Initial Cable pretension

c) Construction Stage analysis

d) Time dependent Material Analysis

9



Analysis Procedure

Final Stage Analysis:

The starting point for design of a cable stayed bridge is an idealised stressed state at a given

time

This is defined as the “Final Stage”

Static and Dynamic analyses

and section design are

---------undertaken using th

e final stage

The construction sequence and cable

installation forces are developed such

that the final stage is achieved at the

given time

10



Analysis Procedure

Cable bridges are highly redundant structures

• This gives the designer flexibility to prescribe a set of cable forces that will achieve a preferred

final stressed state for the deck, pylons and cables under a given loading condition (dead + SDL)

Deflection

Deck Moment Distribution

Instantaneous Dead Load Instantaneous Dead Load + Cable Prestress Forces

Deflection

Deck Moment Distribution

11



Analysis Procedure

Design Stage Construction Analysis:

•Objectives of design stage construction analysis

• To determine the forces in the cable stays at each construction stage

• Check stresses in the girder, pylon and cables at each construction stage

• Check deformations of the structure at each construction stage

•Assumptions

•Adopt an assumed construction sequence

•Assumed construction loading and ambient conditions

Arrive at the design final stage condition

12



Introduction to Extra Dosed Bridge1

Contents

Gyumjae Bridge Project2

13



2. Project outline

Name

Goal

Construction scale

Gyumjae Bridge Basic Design of Construction [Developed by: Seoul Department

of Transportation]

Construction of a Bridge and Highway to connecting Dong Dae Moon Gu Hwui

gyung dong and Jung Lang Gu Myun Mok Dong and deal with the expected

development and traffic flow with Mang Woo Ro, Sa Ga Jung Gil, Dong 2 Ro, Ha

Chun Ro, and etc.

Construction scale

- Total span: 1,085M

- Bridge Length : 393M

Across length of Jung-lang stream: Width 24M, Total Length 225M

Connecting bridge: Width 15M, Length 168M

- Expansion of road: Width 30M, Length 692M

Location The Bridge is located between the three way of Hweekyung Middle and High

School of Dongdaemungu Hweekyung dong, and four way of Junglanggu Myunmok

dong Dong 2 Street.

14



3. Project Location

Total Length: L=1085m

Road expansion: B=30m, L=692m

Main Bridge: B=24m, L=225m

Connection Bridge: B=15m, L=168m

15



4. Structure of Steel Arch Bridge

Pla

nS

ection

Estimated cost of Construction

Budget assumed : $19.87 Million

(Nielsen Arch : $4500/㎡)

Underestimated Construction budget

at preliminary design

$13.54 Million (Arch : $3200/㎡)

Transverse Section

Discu

ssion

◎ Bridge Dimension

Interference between the bicycle path and pier

Irregular span ratio of the main and the connected Bridge

(1:3.5:1)

Lack of originality since Ihwa Bridge which is

preliminary designed has the same structure

L = 40.0 + 140.0 + 40.0 = 220.0m,

B = Nielsen Arch : 24.9m

16



Pla

nS

ection

Discu

ssion

◎ Bridge Dimensions

The form as an Extrodosed Bridge will be the first trial in Seoul

but has been imported actively recently

Maximizing the wide open view for the users by locating the Main tower and

Cables in the center

Estimated cost of Construction

About $18.16 Million

(Unit Construction cost: $3400/㎡)

Transverse Section

L = 60.0 + 105.0 + 60.0 = 225.0m, B=23.74m

4. Structure of Extradosed Bridge

17



Cable arrangements

FAN arrangement

Harp arrangement

Number

of Cables

7 lines on

one side

(0.6”-27)

(0.6”-29)

(0.6”-31)

Main

Tower Height

H=10,12,14m

L=105.0m

(L/8~L/12)

Section

Uniformed section

H=2.5m

L=105.0m

(L/30~L/60)

Cable arrangement:FAN arrangement

Number of Cables: 7 lines (0.6”-29EA)

Height of the Main Tower:H=12.0m (L/8.75)

Section: Uniformed Section 2.5m(L/40)

Optimum Design of Bridge

Pre

limin

ary

Desig

n

EXTRADOSED Bridge with main tower, 3 span

18



Bird’s eye view

19



Driver’s eye view

20



Transverse section – Main Bridge Transverse section – Connected Bridge

Side Perspective

21



5. Construction Method

1) Construction method of EXTRADOSED PSC BOX GIRDER Bridge

The current construction methods of Extradosed PSC BOX Girder Bridges can be categorized in FSM (Full

Staging Method) or BCM (Balanced Cantilever Method).

Construction Method F.S.M

B.C.M

Full Staging Method

Balanced Cantilever Method

Name

Characteristics of the Construction Method

Restrictions Duration Economic Constructability

F.S.M

Restrictions by the bottom

conditions are crucial,

depending on the supporting

system. Restricted by Weather

Construction is fast due to

the lumped pouring method.

Economical efficiency is

determined by the height of the

supporting.

Lower pier is more cost-effective

There are plenty of domestic

bridges constructed by this method.

Easy to construct

B.C.M

Less restrictions by the bottom

condition, weather, and

environment

Slow construction due to

forward construction stage

method

Cost-effective if higher pier or if

there is limited space underneath

the bridge. For instance, bridge

over rail road, bridge over the

sea.

Construction management is

complicated due to having

measurements of each stage.

Similar construction of each stage

will increase the skill to construct

another stage.

22



1) F.S.M construction (1/2)

The F.S.M. construction applied for P.S.C Box Girder bridge is a method continuously pouring concrete on site.

The method installs supports for the entire area till concrete gains its proper strength.

The supports are intended to uphold temporarily the self weight of the concrete, concrete forms, and workbenches.

Introduction

Low cost of equipment, simple method of construction

Cost effective for level ground and low bridges

Fast construction, stable supports during construction

Mostly used for PSC BOX Girder bridge

Characteristics

Fully supported Girder Supported

Classification

Partially supported

23



The order of Construction

Install supports

Install platform

Install concrete form

Install Reinforcement, P.S steel

Pouring concrete and cure

Pre-stressing

Grouting

Remove concrete form

Remove supports

1) F.S.M construction (2/2)

24



2) B.C.M Construction (1/2)

B.C.M construction applied for the P.S.C. Box Girder Bridge is a method pouring concrete on site for each segment. The bridge construction is

started with the construction of the cap of the pier and followed by forming segments of the bridge by using a special device named Form Traveler.

Introduction

Little effect of supporting conditions

Possible for constructing long suspension bridge without heavy duty equipment

Less weather effect

Accuracy of the construction can be enhanced by the correction of errors at each construction stage.

Precise construction and management needed due to changes in the structural system by each construction stage.

High construction fee compared with F.S.M

Characteristics

Continuous arrangements of Sheath which places the reinforcement

Accurate calculation of friction loss and CAMBER management for each construction stage

Disperse of the stress applied to reinforcement connections

Secondary stress due to creep and shrinkage of concrete

If the assumptions change during construction, design should also change with reflecting Feed-Back to construction.

Since the creep and shrinkage of concrete and the relaxation of the reinforcement are considered, the follows should be taken into consideration.

Considerations

25



Order of Construction

Assembling Construction

vehicle (F/T)

Start of Construction

Construct supports

Completion of successive support

constructionAssemble Construction

FormAssemble

reinforcement

Assemble Sheath pipe

Pouring/curing concrete

Tension of reinforcement

Grouting

Construct pier, temporary supporting

system and the main tower

Construction of SEGMENT

Construction of side-span support

Water proof of bridge surface

Finish

Move and re-construct the form traveler

Completion of the 1st span / move the

form traveler

Construct the connection

rep

eat

2) B.C.M Construction (2/2)

repea

t

26



6. Structural analysis of each construction method

1) Analysis of each construction based on Elastic Link (Compression only) of midas Civil

Examine the principle role of Elastic Link (Compression Only) for midas Civil construction stage

analysis by using a simple example of Prestress Concrete structure with temporary support

Explaining statically indeterminate structure with displacement method

Compression Only stiffness of the Elastic Link is the total force of Compression only added by

each construction stage

Principle

Approach

27



S

A

M

P

L

E

1) Analysis theory of each construction stage (1/5)

The problem includes successive

construction model for P.S.C structure by

FSM, which contains 10m beam, eccentric

distance 350mm, and constant Prestressed

Force applied.

M

O

D

E

L

Modeling is based on midas Civil applying

the supports as Elastic Link Boundary

Conditions (Compression Only K=∞)

Compression Only is the total moment

when Dead Load and Prestressed Force

Loading is applied as compressive condition

is effective and the tension boundary

condition is excluded.

[ K3=K4=K5=K6=K7=∞ ) E ffective E lastic Link (C om pression O nly)K 3 K 4 K 5 K 6 K 7

D ead Load & P restressed Force Loading

10.000

850

150

E lastic Link (C om pression O nly)

M odeling

K 1 K 2 K 3 K 4 K 5 K 6 K 7 K 8 K 9

28



S

A

M

P

L

E

Analysis : Apply displacement method

Calculate the displacement Δ1 of the

statically determinate structure with the total

of Dead & Prestressed Force Loading.

M

O

D

E

L

Calculate springs reaction force by

calculating the displacement of Indeterminate

Force Loading, and the displacement

calculated are indicated as function

F3~F7. Δ2 = f(Fi)

Unknown reaction force is analyzed by

calculating the secondary Indeterminate

Force (Fi) which occurs due to the mean

displacements (Δtot=Δ1-Δ2, Δtot=(K/Fi) ) of

each springs (K3~K7)

Δ tot

Δ 2Δ 1

Δ tot = Δ 1 - Δ 2

Δ tot = f(K /Fi) : Function of Fi & K (stiffness of spring for bents)

= K now n value ( D isplacem ent of D eterm inate B eam )

D ead Load & P restressed Force Loading

Δ 1 = D isplacem ent of D ead & P restrssed Force Loading

Δ 1

F3 F4 F5 F6 F7

Δ 2

Δ 2 = D isplacem ent of Indetderm inte Force Loading

= f(Fi) Function of Fi(indeterm inate Force)


29



S

A

M

P

L

E

Model that applied Elastic Link (Compression only) to each temporary support

Tendon 1

10.000

850

150

A p= Φ 12.7- 3E A

1.500

850

150

F

S

M

M

O

D

E

L


30



D

E

A

D

+

P

T

M

O

M

E

N

T

(1)

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

-3.8

14250(Stress) 14250(Stress)

2 .857 2.985

-2.679

-2 .679 -0.453 -0.453

-2.679

-2.679

2.985 2.857

MIDAS/Civil

POST-PROCESSOR

BEAM DIAGRAM

MOMENT-y

2.98548e+000

2.47056e+000

1.95564e+000

1.44073e+000

9.25809e-001

4.10892e-001

0.00000e+000

-6.18942e-001

-1.13386e+000

-1.64878e+000

-2.16369e+000

-2.67861e+000

STAGE:CS1

CS: Dead Load

Last Step

MAX : 9

MIN : 7

FILE: PSC BEAM-B~

UNIT: tonf·m

DATE: 11/09/2005

VIEW-DIRECTION

X: 0.000

Y:-1.000

Z: 0.000

-13.526

-5.000 0.897 0.892 -0.305 -0.305 0.892 0.897

-5.000

-13 .526

MIDAS/Civil

POST-PROCESSOR

BEAM DIAGRAM

MOMENT-y

8.97181e-001

0.00000e+000

-1.72517e+000

-3.03634e+000

-4.34752e+000

-5.65869e+000

-6.96987e+000

-8.28104e+000

-9.59221e+000

-1.09034e+001

-1.22146e+001

-1.35257e+001

STAGE:CS1

CS: Summation

Last Step

MAX : 8

MIN : 1

FILE: PSC BEAM-B~

UNIT: tonf·m

DATE: 11/09/2005

VIEW-DIRECTION

X: 0.000

Y:-1.000

Z: 0.000

Moment Summation Dead Load Moment


31



M

O

M

E

N

T

(2)Tendon Primary Moment Tendon Secondary Moment

5 .669 11.338

17.006 17.006 13.732 13.732 17 .006 17.006 11.338

5.669

MIDAS/Civil

POST-PROCESSOR

BEAM DIAGRAM

MOMENT-y

1.70065e+001

1.54604e+001

1.39144e+001

1.23683e+001

1.08223e+001

9.27625e+000

7.73021e+000

6.18416e+000

4.63812e+000

3.09208e+000

1.54604e+000

0.00000e+000

STAGE:CS1

CS: Tendon Secon~

Last Step

MAX : 3

MIN : 1

FILE: PSC BEAM-B~

UNIT: tonf·m

DATE: 11/09/2005

VIEW-DIRECTION

X: 0.000

Y:-1.000

Z: 0.000

-13.526 -13.526 -13 .526 -13.526 -13.526 -13.526 -13.526 -13.526 -13.526 -13 .526

MIDAS/Civil

POST-PROCESSOR

BEAM DIAGRAM

MOMENT-y

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

-1.35257e+001

STAGE:CS1

CS: Tendon Prima~

Last Step

MAX : 1

MIN : 1

FILE: PSC BEAM-B~

UNIT: tonf·m

DATE: 11/09/2005

VIEW-DIRECTION

X: 0.000

Y:-1.000

Z: 0.000

Summation DeadTendon

Primary

Tendon

SecondaryRemarks

F3 -1.68 -10.62 0 8.94

+ Tension (tonf)

- Compression (tonf)

F1, F2, F8, F9 are excluded

F4 -4.74 -1.65 0 -3.09

F5 -3.86 -3.5 0 -0.36

F6 -4.74 -1.65 0 -3.09

F7 -1.68 -10.62 0 8.94

Axial Load of Springs (ton)


32



Steps of Construction

2) FSM construction stage analysis (1/4)

종 단 면 도 개 요

하부 기초시공

교대 및 교각 시공

A1

P1 P2

A2

1단계 공사

주형 1단계 상부거더 설치용 동바리

주형 1단계 거푸집 설치및 철근

4단계 공사

주탑부 시공

A1

P1 P2

A2

H.W.L 17.05

A1

P1 P2

A2

5단계 공사60.000m105.000m60.000m

60.000m105.000m60.000m

16.000m

동부간선도로

(B=14.0X4.7m)

주형 1단계 콘크리트 타설

A1

P1 P2

A2

2단계 공사

(1단계 타설)

74.500m

75.000m


주형 2단계 거푸집 설치및 철근

A1

P1 P2

A2

75.000m

(2단계 타설)

74.500m

15.000

사재케이블 Pylon1 Pylon2 대칭으로

2단계 상부거더 설치용 동바리 철거

H.W.L 17.05

74.500m

74.500m

3단계 공사

16.000m

동부간선도로

(B=14.0X4.7m)

16.000m

동부간선도로

(B=14.0X4.7m)

동부간선도로

(B=13.0X4.7m)

동부간선도로

(B=13.0X5.93m)

16.000m

동부간선도로

(B=14.0X4.7m)

동부간선도로

(B=14.0X5.97m)

동부간선도로

(B=13.0X4.7m)

15.000

(1단계 타설)

면목역

면목역

면목역

면목역

면목역

휘경여중고

휘경여중고

휘경여중고

휘경여중고

휘경여중고

STEP

거치

가공조립

거치

가공조립

주형 2단계 콘크리트 타설


철거

1단계

2단계

3단계

4단계

5단계

74.500m

15.000

동부간선도로

(B=13.0X4.7m)

74.500m

15.000

동부간선도로

(B=13.0X4.7m)

상부주형 시공완료

내측부터 순차적으로 거치 및 긴장

Pylon1 Pylon1

시공완료

(1단계 타설)

(1단계 타설)

1

2

3

4

5

Profile

33



1st Construction Stage: Model and activate side span temporary supports by Elastic link and Support

2nd Construction Stage: Remove side span temp. supports, and activate temp. supports of main span

3rd Construction Stage : Activate the main tower and place the diagonal tension-cables in order


Structural Analysis of each construction stage using MIDAS CIVIL

34



4th Construction Stage: Complete diagonal Tension Cables, and remove temp. supports of main span

5th Construction Stage : Pavement and Finishing => Completion of Construction

Design Condition

① Structure: 3 span continuous EXTRADOSED P.S.C BOX Bridge ② Grade: Excellent

③ Dimensions: L = 60.0 + 105.0 + 60.0 = 225.0 m ③ Bridge Width: B = 23.740 m (4 lanes both way)

⑤ Thickness: H = 2.50 m (equal section) ⑥ Inclination: S = (±) 0.5 %

⑦ Plane surface alignment: R = ∞ ⑧ Construction method: F.S.M (Full Staging Method )

⑨ Prestress construction: Post-Tensioning Method

Structural Analysis of each construction stage using Midas Civil


35



Upper Combined Stress (Mpa)

Allowable Tensile Stress:

3.20 Mpa

Maximum Tensile Stress:

0.24 Mpa

Allowable Compression

Stress:

-16.00 Mpa

Maximum Compression

Stress:

-10.10 Mpa


Lower Combined Stress (Mpa)

Allowable Tensile Stress:

3.20 Mpa

Maximum Tensile Stress:

0.88 Mpa

Allowable Compression

Stress:

-16.00 Mpa

Maximum Compression

Stress:

-11.75 Mpa

36



1st Construction Stage: Construct Main Pier and Pylon

`

2nd ~9th Construction Stage: Employ F/T Seg. Construct Diagonal cables

10th Construction Stage: FSM construction for Side Span and apply Pylon1girder Time Load as 255 days

Structural Analysis of each construction stage using Midas Civil

3) BCM Construction Stage Analysis (2/4)

37



7. Economical Analysis

F. S. M B. C. M

Equipment,

Maintenance &

Operation time

Equipment Time Equipment Time

Construction time of temp. supports for Side-Span

Maintenance time of temp. supports for Side-Span

Maintenance time of temp. supports for Side-Span

& Main Span

Maintenance time of temp. supports for Main Span

20 days

14 days

21 days

21 days

8Seg. × 15 days (Time per each Seg.)

Side Span Key Seg. Connection

Main Span Key Seg. Connection

120 days

30 days

30 days

Maintenance time of temp. support placed in water2.5

monthsF/T Operation time 6 months

Cost

Quantity Cost Quantity Cost

Temp. support 11.2M

(USD)

F/T(4 vehicle of 2 group)

Set up, pull down (twice)

Operation Cost

1

1

35 Seg.

1.8M

0.3M

0.05M

Camber 35 times 0.15M

Net Construction

Cost13M (USD) 14.1M (USD)

38



8. Conclusion

Cost effective

For applying F.S.M. there has been 10% reduction of the construction Cost.

Construction B.C.M has a long term of construction since it requires accuracy of managing Camber and

several Seg. Construction stage.

Applying F.S.M workability increases and construction time can reduce

Comparison and analysis of applicative and efficiency B.C.M. with F.S.M.

⇒ F.S.M. is cost effective, easier to construct, structurally conservative than B.C.M.

For considering restrictions of lower part of F.S.M., midas Civil uses Elastic Link-Compression only function to

analyze each construction stage and optimizes the temporary support usage plan

Analyzed for the considerations of constructing Gyumjae bridge which is construction above Junglang river,

construction over east-west highway, flood control. ⇒ Comparison and summary of analysis of F.S.M. and B.C.M.

using equal section height of 2.5m Extradosed Bridge.

39



Dead Load

B.C.M: Maximum negative moment on supports are relatively greater than Maximum

positive moment in the middle point. The moments are concentrated to the supports.

F.S.M: The moment of the supports and the middle point are relatively balanced.

Moment after 10,000 days

Method F. S. M B. C. M

Dead

Load`

Mid-point 255,900 kN-m 22,540 kN-m

Support -384,800 kN-m -531,500 kN-m

Structural analysis comparison(1/9)

40



Cable Force

Reaction force of the moment force due to Dead load

Since on B.C.M positive moment does not occur for diagonal cable forces and the resistance force of

cantilever beam dead load is required, the stress distribution to diagonal cables can be higher than F.S.M.



Cable

Force`

Mid-Point -212,000 kN-m 0 kN-m

Support 297,900 kN-m 449,900 kN-m


41



Dead + Cable Positive moment of B.C.M is twice smaller than Positive moment of F.S.M

Negative moment also occurs very small and B.C.M shows profitable stress distribution.



DEAD +

CABLE`

Mid-Point 48,840 kN-m 27,560 kN-m [56.4%]

Support -86,890 kN-m -81,540 kN-m [93.8%]


42



Tendon Primary

For B.C.M construction Cantilever Tendon is added on the upper part to resist excessive negative moment.(Efficient to place internal tendon especially bottom tendon)

For F.S.M. construction it is difficult to place certain tendon at the negative and positive moment. Comparing the sum of moment BC.M. shows more efficient aspect on Positive and Negative moment.



Tendon

Primary

Mid-Point -70,400 kN-m Total : -21,560 kN-m -57,830 kN-m Total : -30,270 kN-m

Support 62,950 kN-m Total : -23,940 kN-m 80,620 kN-m Total : -920 kN-m


43



Tendon Secondary

Tendon Secondary Moment is decided by placement and the amount of tendon. F.S.M.

shows efficiency in both positive and negative moment.

However, in the total sum B.C.M. shows efficiency in analysis.



Tendon

Secondary

Mid-Point 33,390 kN-m Total : 11,830 kN-m 38,940 kN-m Total : 8,670 kN-m

Support 23,200 kN-m Total : -40 kN-m 5,500 kN-m Total : 4,580 kN-m


44



Creep Secondary

Creep Secondary Moment behaves similar to the case of Dead Load.

In the total sum of positive moment B.C.M. shows efficiency but, in the negative moment

since the Creep Secondary acts F.S.M. show efficiency.



Creep

Secondary

Mid-Point 4,639 kN-m Total : 16,469 kN-m 0 kN-m Total : 8,670 kN-m

Support -16,950 kN-m Total : -17,690 kN-m -35,730 kN-m Total : -31,150 kN-m


45



Shrinkage

Secondary

Shrinkage Secondary Moment shows similarity in both method.

Similar to Creep Secondary moment the total sum of positive moment B.C.M. shows

efficiency but, in the negative moment since the Shrinkage Secondary acts F.S.M. show

efficiency.



Shrinkage

Secondary

Mid-point 9,980 kN-m Total : 26,449 kN-m 9,177 Kn-m Total : 17,847 kN-m

Support -13,230 kN-m Total : -30,920 kN-m -15,060 Kn-m Total : -46,210 kN-m


46



Conclusion of

Stress analysis

Structural analysis shows that on the final combination both Method of construction has

similar results.

For stress aspect F.S.M. shows greater and conservative. However since the placement

of Continuity Tendon is functioned to greater section force, it is inefficient for placing

tendon.

Special Loads (D + CF + LI + PS1 + PS2 + CRSH2 + SD)


Upper limit

stress

(MPa)

Bottom limit

stress

(MPa)


47



Diagonal stress

of each

Construction stage

The results of equally sectioned (H=2.5m) and 7 (0.6”-29EA) diagonal cables placed shows

that B.C.M. contains construction stages that exceed the allowable stress and becomes

conservative at the final stage.

Therefore for equal section, diagonal force is greater in B.C.M. and becomes conservative

after constructing continuous⇒ For applying B.C.M varing section is more efficient.


PY-1

Mid-span

Diagonal

Stress

Construction Allowable Max: 4,221kN Min: 3,554kN Allowable Max: 4,746kN Min: 3,687kN

Finish 4,585 kN Max: 4,109kN Min: 3,833kN 4,585 kN Max: 4,126kN Min: 3,874kN

3200.0

3400.0

3600.0

3800.0

4000.0

4200.0

4400.0

4600.0

4800.0

1단계

2단계

3단계

3-1단계

3-2단계

3-3단계

3-4단계

3-5단계

3-6단계

4단계

5단계

완공단계

시공단계

사재

장력

(kN

)

허용응력

C8

C9

C10

C11

C12

C13

C14

3200.0

3400.0

3600.0

3800.0

4000.0

4200.0

4400.0

4600.0

4800.0

1단계

2단계

3단계

4단계

5단계

6단계

7단계

8단계

9단계

10단계

11단계

12단계

완공단계

시공단계

사재

장력

(kN

)

허용응력

C8

C9

C10

C11

C12

C13

C14


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