Application of construction in preflex composite girder with loading

  A SPECIAL FEATURE
   1. A summary of the method
      (Patent a public notice  Number. 10-2000-0036947),
      (Registration number. 20-0196863-0000, Registration number20-0210596-0000)

    The building construction using the basic preflex beam is difficult to obtain     vacant room effectively because of the bigger negative moment rising in     connection with column of section part than positive moment rising in central parts when design load is acted, and brought rusting of steel and a declination of durability because of rising cracks of concrete , and gave damages of connection parts of a pole and a crossbeam, and gave magnification of column section because of increasing of dynamic load being due to excessive dead load.
    the applicable method of the successive preflex composite beam using     loading produces positive moment with stocking a little load to the central     parts of Beam after leaving preflex beam producing as simple beam state     simply between pole and pole, and decline tensile force confronting design     load with using a compressed power of beam section part originated from     excluding the stocked load after continuity with connecting preflex beam and beam by welding

  2. effect

   · the continuous structure using the basic preflex composite girder  was    unavoidable interpretation, but preflex composite girder  using this method can maximize a section effects being due to possibility of interpretation as composite beam

   · efficiency as rahmen can be maximize because perfect firmness is possible between beam and pole

   · that can maximize the efficiency of member and space

   · that can repress damages of connection between pole and beam effectively and  aseismicity is excellent.

   · rusting of bar and steel can be improved being due to controling fissures rising from floor slab concrete

   · Construction is easy and reliable because this method connect between beam and beam inside pole of simple beam situation.

   · when you apply this method , you can decline about 20% of the material cost.

   · this method can be applied to plate girder, p.s.c girder, and so on as well. 

Application of construction in preflex composite girder with loading

  THE METHOD OF MAKING

 1. we make a large quantity of preflex beam in factory and transport to the actual spot of cause, we can make in the actual spot.

 2. in case of concrete pole , we should do placing and curing pole , and should draw out steel which is needed in case of steel composite pole, we should do  placing  and curing concrete in low parts which is stayed by beam , and we should obstruct bucking of pole, and we should make a situation of  putting simply preflex composite beam, welding braket to the web part of steel.

Fig 1 Concrete Column

Fig 2 Steel Composite Column

 3. you should leave simply preflex to the pole in this time , in concrete cases ,     you should do boring to the lower part casing concrete of section part and to     the upper-lower part flange, and then you should help steel of pole can be     penetrated.

Fig 3 Concrete Column

Application of construction in preflex composite girder with loading

 

Fig 4 Steel Composite Column

 4. you connect lateral stiffening , at this time , in case of concrete pole , you do boring to the upper-lower part flange laying in the pole , and then you do penetrate steel. you connect span central lateral stiffening with preflex beam as main beam in similar methods like picture 5.

picture 5. - connection details picture of  preflex beam and lateral stiffening
main beam cross beam The lower casing concrete

 5. you do stock vertical load to the  preflex beam leaving , you can do stock load with establishing anchor in basic bottom in first floor, you can do stock load with laying in floor slab concrete and coiling in the main beam of lower part floor pc strong line in second floor , the picture 8 shows the picture of bending moment being owing to self load and load stock, and picture 9 express the methods stocking load with being tense pc strong line as tension equipment ,and express the methods stocking load with laying in anchor in the basic bottom as basic picture.

picture 6- situation picture of stocking load to the preflex beam in cases of

Application of construction in preflex composite girder with loading

picture 7. situation picture stocking load to the preflex in cases of steel composite column.

picture 8. Moment picture of preflex as beam self load and load stock

Application of construction in preflex composite girder with loading

 6. in cases of concrete pole , we do weld and connect using cover plate between  preflex beam as main beam of simple setting state and beam in cases of steel composite pole, we make successive structure with welding and connecting preflex beam using joint bar in the web part of pole. the picture 10~12 show details of connection between main beam and lateral stiffening to the part of pole in case of concrete pole. he picture 13 shows details connection between main beam and lateral stiffening in case of steel composite column

Fig 10

Fig 11

Application of construction in preflex composite girder with loading

 

Fig 12

Fig 13

Application of construction in preflex composite girder with loading

 7. Upper column, floor slab have simultaneous placing and curing. As column and beam become one body , they can composed behavior in given load. Picture 16 is bending moment diagram that is happened in preflex composite beam of continuous structure state about load of it hasn't set concrete.

 

 Picture 14 concrete column

 Picture 15 Steel composite  column

 Picture 16  that is happened in preflex composite beam of continuous structure state about load of it hasn't set concrete.

 8. Surcharged load is remove. This time,  as bending moment of picture 18 is     happened.  as a result of this, section of beam is introduced and negative     moment by service load is resisted as floor slab and composited beam.

Picture 17  upward force by removed weight

Application of construction in preflex composite girder with loading

 Picture 18 bending moment  diagram of preflex composite beam  is happened by load removed.

 From picture 1 to picture 18, the negative moment section of the construction  process introduced compressed stress and have resisted negative moment by dead load, service load.
 Because this method have decreased exaggerative moment at union part of beam and column, can prevent a lack of water by union part floor concrete's crack at previous construction.
 So this has not only  improvement of endurance but also decrease of column section as well as decrease of beam steel height. As this result can  cut down on  material cost, maximize efficiency of space, make possible production of construction that have improved aseismicity by self load reduction of beam and continuance.
 This method can applied not only preflex beam but also P.S.C continuance beam, Plate gird, steel box. naturally this method can applied on repetition of a same way at continuance of 3 span over.

If show by a diagram construction step and way of this method.

  

Application of construction in preflex composite girder with loading

  example of  a design

 1.examination section in case of possession load 0.5 ton/m2 (Using of SWS 490) - when load 20 ton.

 

picture19

  Section of inner part span length 30m part by this loading used method

    1. To  simplicity of structural calculation, selection predicted the upper center part that will get the most load.  Span of main beam  is 25.0m+30.0m+25.0m=80.0m, Modelling Space of main beam  is 3@10.0m =30.0m.
    2. Structural system is modeled classified by each construction stage  that presented above.
    3.Computation of load
       - acting possession load on floor slab  : 0.5 ton/m2  
       - Self load of lateral stiffening member. :0.12 ton/m
       - Self load of slab :  is applied load of 0.375 ton/m2 over
    4. Stress  examination
 Examination of stress is examined that the most moment is applied 30m span's main beam as steel upper flange's stress of negative moment part in preflex composite beam and lower casing concrete's stress of span center part.

    -The section property

 negative moment part  


positive moment part steel + lower casing concrete

 steel +lower casing concrete +floor slab

I


1516520.8

2052417.5

2723094.6

Yu


48.5

 62.2

69.2

YL


48.5

 47.8

55.8

Application of construction in preflex composite girder with loading

  

 stage

 moment(t.m)

stress(Kg/)

part of end

center

 steel upper flange of end part


lower casing concrete of center


 preflex beam
(early creep, early shrinkage,  consideration of self load)

 

 

0

-165.85


 loading

0

150

0

46.6


Self loading of floor concrete and lateral stiffening member.

-340.6

180.6

1089.5

56.1


 Removal of load

77.8

-81.4

-155.0

-22.2


 loading of  occupation load

-371.5

217.3

739.5

59.4


 Sum

1465.5

-26.0

 
   -The next is expressed stress of section that in case of unloading and considering by classified loaded magnitude  in 30m section.

 

 a reference

 steel upper flange's stress of negative moment part


 lower casing concrete's stress of span cente


unloading

2097

-50.4


loading 5ton of this method

1603

-44.3


loading 10ton of this method

1557

-38.0


 loading 15ton of this method

1511

-32.0


loading 20ton of this method

1465

-26.0

   here, in case of unloading, the reason that stress of steel upper flange in negative moment part grow bigger suddenly, compressed stress hasn't introduced on floor slab concrete of section part by loading removal so because it isn't considered as composite section.

Application of construction in preflex composite girder with loading

 2. examination section in case of possession load 1.2 ton/m2  (Using of SWS 490)

picture20  Section of inner part span length 30m part by this loading used method

  - At same condition such (1), Only possession load applied as 1.2 ton/m2.
  - The next is expressed stress of section that in case of unloading and considering by classified loaded magnitude  in 30m section.

 

 a reference

 steel upper flange's stress of negative moment part


 lower casing concrete's stress of span cente


unloading

2051

-66.7


loading 5ton of this method

1528

-63.8


loading 10ton of this method

1500

-60.8


 loading 15ton of this method

1473

-57.8


loading 20ton of this method

1446

-54.8

    
    here is on equal terms, in case of unloading, the reason that stress of steel upper flange in negative moment part grow bigger suddenly, compressed stress hasn't introduced on floor slab concrete of section part by loading removal so because it isn't considered as composite section.

Application of construction in preflex composite girder with loading

  effect by this method

  As mentioned, compared with section of previous preflex continuance beam that can maintain stress of negative moment part in similar level, section of this method can reduce about 5% of steel and 45% of the lower casing concrete.