4. Criterion of Rebar arrangement

1) Rebar coating▶It means the shortest distance to the surface of concrete to cover rebar surface.

Rebar coating thickness of each part must be considered in the period of plan after

considering durability, refractory, safety in structure endurance & errors in

construction carry-out.

▶There are examples of coating case as ground criterion for all construction without

segmenting the case of ground and also the case of foundation regularly.

※ By the effect of CO2, humidity, acid gas, there will be going on of neutralization

step by step from the surface of concrete.

If the coating is small, its speed to arrive rebar will be faster .

If so, the rust will expand, the adhesion of concrete coating will drop, white

phenomenon will exist, senility of structure body will facilitate.

※ Note : “direct exposure to the air of outdoor” means the case of direct exposure of

climate change and humidity change.

Concrete pouring under water

Concrete burying under ground foreverafter land pouring concrete adjoined

Concrete part to expose to outdoor

air and to adjoin land directly

Concrete part not to adjoin land and

outdoor air

Foundation

Foundation

Wall, pillar

Beam (outside exposure

beam)

Slab(foundation slab)

Slab, Wall, Under Flooring

Beam, Pillar

Shell, Member

Minimumcoating/thickness

100

80

60

50

40

40

20

40

20

RemarkRebar Size

All rebar

All rebar

over HD29

below HD25

below HD16

over HD35

below HD35

TiehoopStirrup

Spiral rebar

All rebar

Classification

(Unit:mm)

※Regarding wall, horizontal rebar should be arranged to the outside of vertical rebar.

※Regarding outside wall in underground which compressed by the land, more

arranged rebar should be arranged to the outside after comparing the arrangement

quantity between vertical rebar and horizontal rebar.

< Independentfoundation >

< Beam > < Wall & Slab >

< Pilefoundation >

< Pillar >

Coatingthickness 80

Coatingthickness 80

Coatingthickness 40

Coatingthickness 20

In Shear wall, thearrangement of rebar

should be to the insideof vertical rebar.

Wall

Coatingthickness

Coatingthickness 50

Hoop

Lean Concrete

StirrupSlab

Lean Concrete

Cushion

Coatingthickness

2) Rebar distance

3) Type of tyingRegarding the working of tying , there are folded tying(lap splice) , compressed

tying(welded splice) , mechanical spiral tying(mechanical splice).

But compressed tying(welded splice) , mechanical spiral tying(mechanical splice)

have to be effected over 125% of resistance strength(fy) in plan criterion.

① Folded tying (lap splice)

It is tying method to fold the fixed length from end part to new tying part by using

regular rope currently.

Deformed

rebar

Net Distance

Over 1.5 times of nominal diameter

Over 1.25 times of max. size of thick aggregate.

Over high value in 25mm

Classification

Distance

Net distance

※ Folded tying(lap splice)

※ Regarding beam main bar tying , you must apply B class tying if you don't

mention tying position specially.

But, you can apply A class tying if you want to tying the compressed part of

concrete. (the compressed part of concrete : upper part main bar places near center

part of span, lower part main bar places near pillar)

ConcreteStrength

(kgf/Cm2)

210

240

270

210

240

270

21.6d

28.8d

RebarSize

Under D19

Over D22

Under D19

Over D22

Under D19

Over D22

Under HD19

Over HD22

Under HD19

Over HD22

Under HD19

Over HD22

31.5d (41.0d)

39.3d (51.1d)

29.4d (38.2d)

36.8d (47.8d)

27.8d (36.1d)

34.7d (45.1d)

42.0d (54.6d)

52.4d (68.1d)

39.2d (51.0d)

49.1d (63.8d)

37.0d (48.1d)

46.3d (60.2d)

41.0d (53.3d)

51.1d (66.4d)

38.2d (49.7d)

47.8d (62.2d)

36.1d (47.0d)

45.1d (58.6d)

54.6d (71.0d)

68.1d (88.5d)

51.0d (66.2d)

63.8d (83.0d)

48.1d (62.5d)

60.2d (78.2d)

1. The length of folded tying of rebars which have different diameter must over high value between the fixed

length of high diameter rebar and the folded tying length of low diameter rebar .

2. The tying position must be placed to low stress / to compressed stress of concrete.

3. By the criterion of concrete structure plan , it is mentioned that it is available for folded tying in case of

D29~D35 rebar.

However, you have to check in advance the problem such as the net distance of rebar is not secured and

also the tying length will be exaggerated if you apply folded tying of thick rebar.

Generally, there are more advantageous case by using mechanical tying instead of folded tying in case of

over D29 rebar.

A class tying : must be zigzag(rotation) tying arrangement and arranged rebar quantity is over 2 times of

required rebar quantity which defined in total block of tying part and also under 50% of rebar tying

quantity within required folded length.

B class tying : it is available for the tying of anti-earthquake plan and generally it is applicable to all

construction site.

Regarding SD500 , you must apply 1.25times of B class tying.

The value in ( ) is the case of upper part rebar.

Tying length of deformed rebar to beextended

Tying lengthof deformedrebar to becompressedA Class TyingA Class Tying

Rebar

Type

SD30

(fy=3,000 )

SD40

(fy=4,000 )

※ The tying length of wall vertical length is available around 40db of under HD19

especially.

Example of folded tying(lab splice)

ⓐ Folded tying of vertical rebar in case the distance of rebar arrangement is different

ⓑ Folded tying of horizontal rebar Example) Length of folded tying to be extended

of vertical & horizontal rebar

Slab upperpart

Verticalrebar

Slab upper part

Tyi

ng L

engt

h of

Tying Length of Tension bar(Ls)Diameter Length

S : Distance of RebarLs : Tying length of Tension bar

Tying

Len

gth of

Fix

ed len

gth of

Tensio

n bar

Ten

sion

bar

(Ls)

Wall

Tens

ion ba

r(Ls)

② Compressed tying(welded splice)

It is the tying method to compress through heat-treatment end to end by using

machinery.

As shown in figure(A) , place 2 bars 3mm away , heat up both of the ends by using

mechanical equipment and add pressure to weld splice them figure(B), usually

available for all bars.

③ Mechanical spiral tying(mechanical splice).

As the mechanical splice method , it is rebar tying method to connect the spiral

part with nut & coupling by cutting screw by expanding the end of rebar over the

regular size.

(A) Connect Nut

(B) Connect Coupler

(C) Move Coupler

(D) Move Nut

4) Fixing and tying① In order to effect the adequate resistance strength of rebar, it is essential to obtain

the enough adhesion strength with concrete.

The more you increase the net distance & coating thickness of rebar, the larger of

adhesion strength.

② Fixing length is the buried length in concrete to effect the adequate resistance

strength of rebar and fix the length with the criterion of max. stress point of

appropriate rebar.

③ The fixing and tying length of rebar is changing by the strength of material and

type of rebar arrangement , etc.

i. It will be lengthen by using HD(high density) rebar.(SD40 is 1.33times of

SD30A)

ii. It will be shorten by using HD concrete.(inverse proportion from square root of

concrete strength)

iii. It will be shorten if net distance and coating thickness of rebar increase.

iv. It will be shorten by the restriction effect if it is surrounded by stirrup and tie

hoop.

④ Caution : If the fixing and tying length of rebar will be shorten , the resistance

strength of rebar will be reduced as long as the shortened length.

Also, in case the heavy binding of splice part of rebar needlessly sometimes,

binding has only the role to prevent the movement of rebar when pouring concrete

and also no relation to adhesion strength of rebar. (the tensile of a D25 rebar is

5.04 4.0=20.16tonf)

⑤ If the position of extended rebar for the tying of poured concrete is wrong, it is

available for bending of splice with the angle of under if error is trivial but you

need to take additional action to increase the section of additional material if error

is over that angle.

⑥ In case slab or wall rebar will be cutted by temporary exit such as material pick-up

exit, etc, you must extend the rebar which is over the length of splice to both ends

of exit.

If width of exit is narrow or the length of rebar extended is shorten , the length of

splice will be shorten when pouring exit concrete later.

⑦ Calculation of bar length

What should be added to original length : splice length, fixed length

Splice length : extra length to lap the bars

Fixed length : developed length when the bar is fixed

⑧ Method to calculate fixed length

⑨ Tension bar and compression bar

tension bar : The main usage is tension bar because rebar is reinforced material

to reinforce the tension of weak point of concrete.

compression bar : the rebar to be arranged in addition to increase the resistance

strength in concrete material and it is mainly applicable to the pillar of high

building to cover the compression.

⑩ Refer to the diagram (#22 page) for tying & fixing per rebar diameter

Splice length

Fixed length

- In case of fixing to neighbor beam -

Compression

Tension

fixed length oftension bar

Fixed length ofrebar which hasstandard hook

- In case of fixing to end pillar -

fixed length of tension bar

90°

Stan

dard

hoo

k

5) Form of fixed beam※ When arranging beam, the marked on drawing as bending bar is mainly Japanese

method of rebar arrangement.

Our standard will be cut-bar instead of bending bar(Japanese method) .

① The length to

extend to reverse

side from max.

Stress point of

fixed length.

Hook should

place over the

center of pillar.

※① is fixed length of tension upper bar.

In case of fixing with standard hook, fixed length of rebar which has standard

hook will be applied.

If not, fixed length of tension bar will be applied.

is generally fixed length of lower compression bar and it is available of

fixation if it is extended to pillar over 15cm without hook.

Fixed length

Stress(part to

effect theweight)

Return point beam

Return point is must not 1/4point. (return point of upper bar isdifferent from return point oflower bar)

6) Example of fixed length per rebar diameter① Fixed length of tensile rebar

Fixed length of tensile rebar in slab(SD 400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

Fixed length of tensile rebar in foundation, pillar, beam, wall(SD400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

HD10

HD13

HD16

HD19

HD22

HD25

HD29

HD32

StrengthRebar

24N/240kgf/

27N/270kgf/

30N/300kgf/

35N/350kgf/

40N/400kgf/

400

510

630

750

1080

1230

1430

1570

510

670

820

970

1410

1600

1850

2050

24N/240kgf/

300

400

540

730

27N/270kgf/

300

380

510

680

30N/300kgf/

300

360

490

650

35N/350kgf/

300

330

450

600

40N/400kgf/

300

310

420

560

Remark

370

490

600

710

1020

1160

1350

1480

490

630

770

920

1330

1510

1750

1930

360

460

570

670

970

1100

1280

1410

460

600

730

870

1260

1430

1660

1830

330

430

520

620

900

1020

1180

1300

430

550

680

810

1170

1320

1540

1690

310

400

490

580

840

950

1110

1220

400

520

640

760

1090

1240

1440

1590

General bar Upper barGeneral bar Upper barGeneral bar Upper barGeneral bar Upper barGeneral bar Upper bar

(unit:mm)

(unit:mm)

StrengthRebar

② Fixed length of compression bar

Fixed length of compression bar(SD400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

7) Example of splice length per rebar diameter

1) Classification of tension splice

ㆍA class tying : must be zigzag(rotation) tying arrangement and arranged rebar

quantity is over 2 times of required rebar quantity which defined in total block of

tying part and also under 50% of rebar tying quantity within required folded

length.

ㆍB class tying : it is available for the tying of anti-earthquake plan and generally it

is applicable to all construction site.

2) Upper bar : horizontal rebar without concrete harded over 300mm under splice part

and fixed length

3) The rebar with folded splice without contacting directly each other in bending

material must not depart over little value between 150mm or 1/5 of folded splice

length.

HD10

HD13

HD16

HD19

HD22

HD25

HD29

HD32

24N/240kgf/

210

270

340

400

460

520

600

670

27N/270kgf/

200

260

300

370

430

490

570

630

30N/300kgf/

200

240

300

360

410

460

540

600

35N/350kgf/

200

230

280

330

380

430

500

550

40N/400kgf/

200

210

260

310

360

400

470

520

50N/500kgf/

200

210

260

310

360

400

470

520

2

2

50% 50%

Actual arranged rebar requirement

Required rebar Q’ty

Max. splice % within folded splice length

(unit:mm)StrengthRebar

① A class splice length of tension rebar

Splice length of slab(SD400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

A class splice length of foundation, pillar, beam, wall(SD400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

② B class splice length of tension rebar

It is available for the tying of anti-earthquake plan and generally it is applicableto all construction sites.

B class splice length of slab(SD400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

HD10

HD13

HD16

HD19

HD22

HD25

HD29

HD32

Rebar

24N/240kgf/

27N/270kgf/

30N/300kgf/

35N/350kgf/

40N/400kgf/

400

510

630

750

1080

1230

1430

1570

510

670

820

970

1410

1600

1850

2050

HD10

HD13

HD16

HD19

Rebar

24N/240kgf/

390

520

700

940

27N/270kgf/

390

490

660

890

30N/300kgf/

390

470

630

840

35N/350kgf/

390

430

580

780

40N/400kgf/

390

410

550

730

Remark

370

490

600

710

1020

1160

1350

1480

490

630

770

920

1330

1510

1750

1930

360

460

570

670

970

1100

1280

1410

460

600

730

870

1260

1430

1660

1830

330

430

520

620

900

1020

1180

1300

430

550

680

810

1170

1320

1540

1690

310

400

490

580

840

950

1110

1220

400

520

640

760

1090

1240

1440

1590

General bar Upper barGeneral bar Upper barGeneral bar Upper barGeneral bar Upper barGeneral bar Upper bar

HD10

HD13

HD16

HD19

Rebar

24N/240kgf/

300

400

540

730

27N/270kgf/

300

380

510

680

30N/300kgf/

300

360

490

650

35N/350kgf/

300

330

450

600

40N/400kgf/

300

310

420

560

Remark

(unit:mm)

(unit:mm)

(unit:mm)

Strength

Strength

Strength

B class splice length of foundation, pillar, beam, wall(SD400)

※When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times

③ Splice length of compression rebar

HD10

HD13

HD16

HD19

HD22

HD25

HD29

HD32

Rebar

24N/240kgf/

27N/270kgf/

30N/300kgf/

35N/350kgf/

40N/400kgf/

510

670

820

970

1410

1600

1850

2050

670

870

1070

1260

1830

2080

2410

2650

490

630

770

920

1330

1510

1750

1930

630

820

1000

1190

1720

1960

2270

2510

460

600

730

870

1260

1430

1660

1830

600

780

950

1130

1640

1860

2150

2380

430

550

680

810

1170

1320

1540

1690

550

720

880

1050

1510

1720

2000

2200

400

520

640

760

1090

1240

1440

1590

520

670

830

980

1420

1610

1870

2060

General bar Upper barGeneral bar Upper barGeneral bar Upper barGeneral bar Upper barGeneral bar Upper bar

HD10

HD13

HD16

HD19

HD22

HD25

HD29

HD32

Strength

Rebar

fck = 21N/ = 70N/ (210kgf/ - 700kgf/ )

SD400 (fy=400N/ =4,000kgf/ ) SD500 (fy=500N/ =5,000kgf/ )

300

380

470

550

640

720

840

930

410

540

660

780

910

1030

1190

1320

(unit:mm)

Strength

④ Fixed length of tension bar which has standard hook fy=400N/㎟(4,000kgf/㎠)

※ When using SD500 rebar(fy=500N/㎟=5,000kgf/㎠), apply 1.25 times.

⑤ Fixed length and splice length of binded rebars.

Increase the fixed length and splice length of binded rebars as follows.

a) 3pcs binded rebars : increase 20%

b) 4pcs binded rebars : increase 33%

The splice of each rebar must not duplicated

HD10

HD13

HD16

HD19

HD22

HD25

HD29

HD32

Rebar

24N/240kgf/

210

270

340

400

460

520

600

670

27N/270kgf/

200

260

300

370

430

490

570

630

30N/300kgf/

200

240

300

360

410

460

540

600

35N/350kgf/

200

230

280

330

380

430

500

550

40N/400kgf/

200

210

260

310

360

400

470

520

50N/500kgf/

200

210

260

310

360

400

470

520

fixed length of tension bar

tension

or3db HD10 ~ HD254db HD29 ~ HD355db over HD38

min

(diam

eter)

(diam

eter)

destroyed section of concrete

Strength

tension