Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

  Improvement of ability and repair&reinforcement method of P.S.C and the     Preflex continuous beam bridge
    ( patent 10-1999-007572, patent 10-1999-045825, patent 10-1999-04582)

 1. Introduction

 1. brief

 beam bridge of P.S.C & Preflex connecting existing simple method is acted constructal moment redistribution. At this time , because it occur negative moment in continuous span , concrete of slab is cracked and problem of a drop bridge' persistence is occured.
 [this method of construction is improvement of ability method  introducing the compressive force using Up-Down Method  at concrete of slab negative moment.
this method improve by DB-24 then existing P.S.C and the Preflex.

2. construction method

 1) this method of construction  part removing slab

  after removing slab at negative moment of P.S.C and the Preflex., it arrange reinforce and make concrete except the section inside support 0.1L. this time, cross beam lower neutrality axis make concrete. then the remander section is made concrete, cure the concrete surface, after down, finish.

 2) this method of construction  entirety removing slab
  
   after removing  the entirety slab., it make concrete at the section positive moment. then cure the concrete surface, up support, it make concrete at the section negative moment, it is finished making bridge by down support.

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

  repair&reinforcement method

 1. simple bridge

 when it need to change slab of existing bridge, equal upper step. only addition  breaking concrete. if existing bridge slab do not change, the step is the next.
 

 

  removing concrete of center girder( preserving existing reinforced rod)

  

 

equipping the temporary support & up girder

 

 

      concrete slab concrete at center and  cure the concrete surface.

 

 

 remove the temporary support and falling girder ( introducing compressive  at the lower part girder) falling

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

 2. continuous bridge

   improvement ability method's step of continuous 2 span P.S.C &     Preflex composite bridge by part removing slab method

 

 production step

 construction step

order chart 

STEP1

part removing slab concrete & connecting 

 

STEP2

 concreting partly slab concrete

 

STEP3

up inner support 

 

STEP4

 entirety removing slab concrete

 

STEP5

down inner support 

 

STEP6

 completion

 

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

  improvement ability method's step of continuous 2 span P.S.C &    Preflex composite bridge by entirety removing slab method

 

production step

construction step 

order chart 

STEP1

part removing slab concrete & connecting

 

STEP2

 concreting partly slab concrete

 

STEP3

up inner support

 

STEP4

 entirety removing slab concrete

 

STEP5

 down inner support

 

STEP6

 completion

 

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

  effect improvement ability of existing bridge

    1. simple bridge

     the subject bridge : the location Imshhil-Gun ,Chollabuk-Do, simple support       PSC Beam bridge, Sasun overhead bridge   
      length of girder 17.4m, length of bridge 18m, wide of bridge 9.25m
      It has been completed at 1973 , the second grade

  effect : The basis durability increases form DB-20 to DB-29

 
<a panoramic view> 


<cross view>

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

  Sasun overhead bridge of The rising quantity, the falling quantity and     occurring stress at final step
 


classification

inner span

outside span


 the rising force

11.97 ton

 13.68 ton


 the falling force

 -17.79 ton

 -19.51 ton


the rising displacement

 0.63 cm

 0.72 cm


the falling displacement 

 -0.42 cm

 -0.46 cm


 final stress


the lower beam

 -2.24 Kg/cm2
(
compressive)

 10.69 Kg/cm2
(tension)


 the upper slab

 -50.66 Kg/cm2
(compressive)

 -56.25 Kg/cm2
(compressive)

 


classification

before improvement of ability 

 after improvement of ability(basic design)

the comparison 

Sasun
overhead
bridge
(L=18.0m)

 
design load

DB_18

DB-24

 


The basis durability

 DB-20

 DB-29

45% increase

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

 2. continuous bridge ( basic design )

    the subject bridge : the location Ulsan city, simple support of 20m span ,       continuous 2 span of 20m span & continuous 3 span of 30m span, PSC       Beam bridge.   
      length of girder 550m
      the second grade
  
  effect : The basis durability increases form DB-18 to DB-37

 
yaemdong direction                                        myoungchondong direction

 myoungchon large bridge's general view

(a) center of span

(b) end point of span

(a) center of span

(b) end point of span

  20m PSC Beam's general view               30mPSC Beam's general view

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

   myoungchon large bridge's of The rising quantity, the falling quantity      and occurring stress at final step

 

  classification


 PSC Beam span L=30m


 continuous 2 span

continuous 3 span 

 the rising force

 24.59 ton

14.28 ton 

 the falling force

 -17.64 ton

 -8.26 ton

 the rising displacement

 6.22 cm

 3.61 cm

the falling displacement 

 -3.86 cm

1.81 cm 

final
stress 

the section of positive moment 

the lower beam

12.31 Kg/cm2
(tension)

10.69 Kg/cm2
(tension)

 the upper beam

 -86.57 Kg/cm2
(compressive)

 -88.50 Kg/cm2
(compressive)

 the upper slab

 -14.79 Kg/cm2
(compressive)

-16.33 Kg/cm2
(compressive)

the section of negative moment 

 the lower beam

 -131.4 Kg/cm2
(compressive)

 -114.71 Kg/cm2
(compressive)

  the upper beam

 16.46 Kg/cm2
(tension)

 -5.42 Kg/cm2
(compressive)

the upper slab 

12.75 Kg/cm2
(tension)

 0.47 Kg/cm2
(tension)

 


 classification

before improvement of ability

after improvement of ability(basic design)

the comparison  

 simple support(L=20m)

design load 

DB-18

 DB-24

The basis durability

DB-18

DB-26

30%
increase 

 continuous 2 span (L=20m)

design load  

 DB-18

 DB-24

The basis durability

DB-20

DB-33

65%
increase 

 continuous 3 span (L=30m)

design load  

 DB-18

 DB-24

The basis durability

DB-20

DB-37

85%
increase 

 

 Improvement of bridge's ability and repair&reinforcement method
Improvement of ability method of simple and continuous span P.S.C
and the Preflex composite bridge by Up-Down Method

  the method connecting at the section inside support

      it is point that bending tension moment at upper girder and bending       compression moment at upper girder for continuing P.S.C and the Preflex       Beam.

   1. method A (P.S.C Beam)

   For bending tension stress at continuing support using chemical anchor at PSC    Beam's upper, it  correspond effectively, and connecting with girder is planed    for compressive stress at lower girder.

Fig. a

Fig. a (the method connecting P.S.C Beam)

    2. method B (Preflex Beam)

    bending tension stress at connecting at the section support at upper girder     and compressive stress at lower girder is corresponded by effectively     connecting Beam and Beam.

Fig. b (the method connecting Preflex Beam)

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of ability method using crack-fasten of P.S.C Beam acting bending crack

  improvement of bridge's ability and repair&reinforcement method *
<improvement of ability method using crack-fasten of P.S.C Beam   acting bending crack>
( patent number 10-1999-007572 ,  patent number 10-1999-045825 ,
 patent number 10-1999-04582 )

1. outline

  Presently existing bridge have many problem. so it require repair & reinforcement
  existing method of repair & reinforcement have variety problem.
  this method of construction overcome the problem of other existing method of   repair & reinforcement : it is made improvement of unreliable injecting by loading   pre-load at structure occurring bending crack and pure into injection. then it is   made improvement of repair & reinforcement by getting rid of pre-load. the   reason is that bending crack concrete occur compressive stress. so this   method of repair & reinforcement is fitting and trusting.

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of ability method using crack-fasten of P.S.C Beam acting bending crack

  construction step and stress view

   

 

 Improvement of bridge's ability and repair&reinforcement method
Iimprovement of ability method using crack-fasten of P.S.C Beam acting bending crack

 

Fig. 2 force of construction by stages

Fig. 3 effect of inducing stress

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of ability method using crack-fasten of P.S.C Beam acting bending crack

  experiment view

       

             (a) loading pre-load                (b) injecting epoxy resins
                                              and curing the concrete surface

Fig. 4 loading pre-load and injecting epoxy resins

        

Fig. 5 being completed hardening of injecting

  table 1 loading-deflection relationship
 

load

deflection before repair&reinforcement

deflection after repair&reinforcement 

 measuring date of experiment

 analysis of finite element

 measuring date of experiment

 analysis of finite element

3

 5.78

6.89

 5.06

5.62

6

 14.16

 13.79

 9.26

 11.24

9

 20.47

 20.68

 13.88

 16.87

12

 25.73

 27.58

 23.94

 22.48

16

 36.4

 36.77

 26.6

 29.97

20

 45.50

 45.96

 37.5

 34.46

24

 -

 -

 45.27

 44.95

28

 -

 -

 52.43

 52.44

32

 -

 -

 60.50

 59.94

34

 -

 -

 65.95

 63.68

37

 -

 -

 72.00

 69.3

  this date is showed : comparing measuring date of experiment with analysis of   finite element

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of ability method using crack-fasten of P.S.C Beam acting bending crack

  comparing a method of construction

   we apply this method to simple PSC composition beam of reinforcing as    External Prestressing method. then  we compare stress condition

   * the subject bridge : moonle overpass
   * the time of completed : 1979
   * type of upper structure :single span PSC composit beam
   * external state : deterioration of slab and girder, crack occur at PSC beam,       bending crack  length 20~80cm, wide 0.1~0.3m. result of crack's deep, crack       exceed reinforce rod's cover.
      so need structural reinforcement.
   *  profile factor's rate : 15%

 

Fig. 6 moonle overpass's cross section

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of ability method using crack-fasten of P.S.C Beam acting bending crack

  table 2 comparing stress in service load
 


 classification

upper section
Kgf/cm
2

low section
Kgf/cm2 

 the comparison

stress
before
damage 

DB-18

-91.23

 12.07

  exceeding allowance stress

DB-24

 -97.88

 32.92

stress after damage

DB-18

 -96.29

 39.89

 DB-24

-102.94

 60.79

External
Prestressing

DB-18

 -77.29

 -12.60

satisfactory
design load 

DB-24

-83.93

8.3

Preloading

DB-18

-91.16

 -4.20

DB-24

-97.81

16.70

 resulting of comparing this method to External Prestressing method by inducing  at simple PSC beam,  the lower part of PSC beam inducing stress quality is  smaller 8.4kgf/cm2 then External Prestressing method, but this method secure  durability except additional repair&reinforcement method.

 

 Improvement of bridge's ability and repair&reinforcement method
Repair method at inner support of continuity Steel Box Girder using injection concrete

  Repair method at inner support of continuity Steel Box Girder using injection concrete

  1. outline

    This method is repair method : after clearing rot, lowering stiffness is repair.

  * rotting of inner support in Box wall
    water store at inner support because  of camber. so it occur rotting of inner     support in Box wall

 Fig. 1 flow of water leakage by camber

 * Repair method using injection concrete

   if rotting of inner support in Box wall is removed like Fig. 2 , thickness of   flange&web is drop and stiffness is reduction.

   

 Fig. 2 Box inner wall occurring rot

 

 Improvement of bridge's ability and repair&reinforcement method
Repair method at inner support of continuity Steel Box Girder using injection concrete

 

  Fig. 3 after removing corrosion

  

 Fig.4 Being reinforced at section negative moment by injecting concrete.

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  1. outline

  Presently existing continuity bridge was constructed without preparing negative   moment at inner support. so slab concrete was cracked and stiffness and   durability was decline. finally, this crack is made dark action as structure and   dark effect as using & durability.
  improvement of continuity bridge's ability method using weight is a method   introducing compressive stress at negative moment inner support. so crack is   prevented and this method have an advantage at deflection & shock.

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

 2. improvement of continuity bridge's ability method using weight

     step 1 removing slab at section negative moment
          

      step 2 loading after repairing across beam

  load is decided by tension reinforced rod quantity and moment . this moment is   that across beam's ability resistant.

      step 3 removing after concreting slab at section negative moment

  through step 1~step 3 , induce compressive stress at section negative   moment's slab. so it is  
  resisted negative moment acting live load. this method is applied at plate   continuous bridge and steel box continuous bridge's repair method and over 3   span.

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  3. structure computation's example

   structure computation perform for ability application this method , actually    constructed 2 span   continuous preflex bridge, using finite element analysis    modeling.
   this modeling is 2 span continuous bridge , span length 45m, this bridge is    location Inchon city,
   public overpass. Fig. 1 is cross section view of preflex bridge. Fig. 2 is cross    section view of 1 preflex beam. Fig. 3 is cross section view of across beam of    section positive moment and section negative moment. and table 1, table 2 is    section's character using  finite element analysis.

 
Fig. 1 cross section view of preflex bridge

 table 1 section's character of preflex beam beam

beam+slab

beam

A

2524

1522

Ix

8678835.2

4581683.8

Iy

4634171

570109.1

J

1885243.8

277118.8

Fig. 2 cross section view of preflex beam

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  table 2 section's character of across beam and slab

across beam

slab

across beam+slab

across beam of connecting section

across beam of connecting section-slab

A

370.6

323.5

694.1

2491.6

2168.1

Ix

340477.9

16850

1087095.2

6110930.9

3897394.0

Ix

27794.1

326225.5

354019.6

2927906.1

2601680.7

J

111176.5

67402.0

178578.5

5880763.4

5813361.0

Fig. 3 across beam and slab

(1) detail construction step

   adhering strut
    a-1. cross section of beam

  

 Fig. 4 crossing section with beam , adhering strut at lower across beam

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  a-2. cross section view of connecting section

 Fig. 5 adhering strut at lower across beam

   b-1. a ground plan ( view at down )

Fig. 6 adhering strut's shape at down

  injecting concrete

    a-1. cross section of beam

Fig. 7 injecting crossing section with beam

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  a-2. cross section view of connecting section

  

 Fig. 8 injecting concrete  of connecting section

    removing slab
      a-1. cross section of beam

Fig. 9 removing upper flange at crossing section with beam

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  a-2. cross section view of connecting section

Fig. 10 removing upper flange at connecting section

    injecting epoxy at section across beam crack
      a-1. cross section of beam


Fig. 11 injecting epoxy at across beam upper cracking section of crossing section


 a-2. cross section view of connecting section

Fig. 12 injecting epoxy at across beam upper cracking section of connecting section

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

  loading

    a) bending moment of ability removing slab's across beam

       * the out side of across beam

  
    M=204.5 tm

     * inner across beam

    

 

Improvement of bridge's ability and repair&reinforcement method
Iimprovement of continuity bridge's ability method using weight

 b) loading weight

result finite element analysis, negative moment 330ton occur when 100ton load at G beam. so weight is 63.3ton for occurring negative moment 204.5ton. so weight is 60ton.

  c) loading weight

*step 1

 Fig. 13 cross section and a ground plan of loading step 1's weight

*step 3

 Fig. 14 cross section and a ground plan of loading step 3's weight

 

 Improvement of bridge's ability and repair&reinforcement method
improvement of continuity bridge's ability method using weight

   concreting slab and release

 

Fig. 15 cross section and a ground plan of concreting slab and release

  (2) final stress

   table 4 final stress of weigh and live load   



the out side of across beam

the inner side of across beam

the point of load


bending moment by live load

412.8tm

412.8 tm


upper stress by live load

28.57 Kg/cm2
(tension)

42.85 Kg/cm2
(tension)


bending moment by weigh

235.32 tm

248.82  tm

147 tm


upper stress by weigh

17.53 Kg/cm2
(compession)

25.8 Kg/cm2
(compression)

21.9 Kg/cm2
(tension)the (section lower casing)


final upper stress

11.04 Kg/cm2
(tension)

17.05 Kg/cm2
(tension)

 

 Improvement of bridge's ability and repair&reinforcement method
repair&reinforcement method of pier's coping

1. outline

  this method repair and reinforce crack acting at pier's coping supporting the   upper part bridge.

   Fig. 1 cracking shape

2. existing method of construction.

 

 Improvement of bridge's ability and repair&reinforcement method
repair&reinforcement method of pier's coping

 

Fig. 2 is existing method of construction. the method have problem of maintaining

existing method using frequently have many problem.

 

 Improvement of bridge's ability and repair&reinforcement method
repair&reinforcement method of pier's coping

 3. construction method

  this method is that: after  it load cracking load at coping of acting crack, extend crack. then using epoxy resins, fill crack, remove load. finishing.

Fig. 3 after cracking load, fill injection

filling injection

3. effect

  this method improve 150~200% of practical coping durability as introducing compressive at total coping.