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