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13. Beam rebar arrangement 1) Principle of beam rebar arrangement Calculate the size and depth of beams according to the drawing and arrange them in a suggested order, that is, exterior beams and big beams(G) & deep beams first and then binding small beams(B beams) later. Supervisor has to check if the bar used at the top span meets the requirement on the drawing. Shorter bar than required might be used to save cost when the span is longer than 8,000mm, the bar standard. The bar might deflect from undesirable vibration when placing concrete if the double reinforcement or top end bar are tied with tying wires. To prevent this, 3 pieces of stirrups are used to tie the bars at the top and as many pieces to place double-leg bar & top bar on the bottom bar. Cap tie bar should carry out 1 by 1 at least. The 1st stirrup should be arranged with the space 50mm from the perimeter of side pillar. @/2 or under 50mm from side pillar @/2 or under 100mm from side big beam <The height will be changed by th rebar size> Stirrup:end support(S.T.) 1st stirrup arrangement beside of pillar’s main bar 1st stirrup arrangement beside of big beam main bar big beam Center support(S.T.)

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Detailed design of steel works, and reinforcements.

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Page 1: Design Details

13. Beam rebar arrangement

1) Principle of beam rebar arrangement① Calculate the size and depth of beams according to the drawing and arrange them

in a suggested order, that is, exterior beams and big beams(G) & deep beams first

and then binding small beams(B beams) later.

② Supervisor has to check if the bar used at the top span meets the requirement on

the drawing.

Shorter bar than required might be used to save cost when the span is longer than

8,000mm, the bar standard.

③ The bar might deflect from undesirable vibration when placing concrete if the

double reinforcement or top end bar are tied with tying wires.

To prevent this, 3 pieces of stirrups are used to tie the bars at the top and as many

pieces to place double-leg bar & top bar on the bottom bar.

④ Cap tie bar should carry out 1 by 1 at least.

※ The 1st stirrup should be arranged with the space 50mm from the perimeter of

side pillar.

@/2 or under 50mm from side pillar @/2 or under 100mm from side big beam

<The height will be changed by th rebar size>

Stirrup:end support(S.T.)

1st stirruparrangement besideof pillar’s main bar

1st stirruparrangement besideof big beam main bar

big beam

Center support(S.T.)

Page 2: Design Details

※ The splice for upper part rebar of beam's end and lower part rebar of beam's center

apply tension splice length.

※ Apply the above except the case of marking separately on beam chart.

※ S1-S4 : stirrup distance

2) Types of stirrup

Ldh

S1 S2 S3

5050

end0.25L1

center0.5L1L1 L2

end0.25L1

end0.25L2

center0.5L2

50

S4

12db

0.3L1 OR 0.3L2 0.3L1 OR 0.3L2

min 15㎝ min 15㎝ or continuance min 15㎝ or continuance0.125L1

0.125L1 0.125L1L1 L2

0.125L2

<Main bar arrangement>

<Distance of stirrup>

- beam without cap tie bar- beam to be arranged by front end without twisting- beam without anti-earthquake plan

① slab on both sides ② slab on one-side ③ no slab on both sides

<a> Open type

<b> Closed type

middle/big value

middle/big value

Page 3: Design Details

3) Position of beam tying(splice)

※ Splice location : diagonal line

① Calculation of bender

When bent bars are used to reinforce beams, bending point of the bar is usually

calculated as distance from the center of the pillar.

However, it is formal to divide it into 4 parts from the end of beam reinforcement

to the other end.

- beam with front end and twist- in case of anti-earthquake plan

wall girder

pillar

over

30c

m

over

45c

m

splic

e ag

ains

t tot

aldi

stan

ce o

f mem

ber

Page 4: Design Details

② An example for processing

Anchorage(fixed) bars are classified as the top bars and the bottom bars, when the

former have tensile loads and the later have compression loads.

Therefore, the top bars and bottom bars set fixed splice length with same method

because it has difficulty in working separately for processing and

assembling.(criterion of concrete structure plan)

In a real construction, 40d is used for both of them for convenience sake.

③ Cover depth of beams

ⓐ Stirrup with spacer should be tied several times.

ⓑ Pay attention when arranging reinforcements in order to have enough cover depth.

4) Bending position of bender (classification of tension & compression)

※ Using the bent bars in beams is Japanese style, while cutoff bar is now in common.

spacer

Y beam

Y beam X beam

X beam

Ten

sion

fixa

tion

Tensionfixation A class tension splice

A class tension splice

bent bar

penetrationof bent bar

top bar

(Top floor)

(General floor)

bent bar

height 40

coverthickness 40

Page 5: Design Details

5) Beam rebar arrangement(CUT TYPE)① In case of beam

② In case of girder

Note

1) * : apply general bars splice length(A class splice) as standard splice length &

fixed length of rebar(22page 6)) for above size

2) ** : fixed as standard hook form about center part bottom bar's 25%

3) splice length according to splice position of rebar arrangement

- tying on upper part rebar(beam) block : apply A class tension rebar splice

tying except upper part rebar(beam) block : apply B class tension rebar splice

- tying on lower part rebar(beam) block : apply A class tension rebar splice

tying except lower part rebar(beam) block : apply B class tension rebar splice

0.3L or 0.3L1 0.3L or 0.3L1

big value big value

0.3L or 0.3L1 0.3L or 0.3L1

big value big valuestandard hookfixed length

Page 6: Design Details

6) Beam rebar arrangement by using stepped pulleyThe types of step are classified as planar step, elevated step, step in material

according to their shapes.

In each case, arrangement is in vertical or in horizontal.

If the worker has no choice but to bend the bar, bend it at low grade.

When the mid span of a beam has steps as shown below left, the bar might be

necessarily bent, which is quite undesirable.

The load tends to straightly pass through.

If pulled out, the bar does not straighten as it looks.

Far from straightening, it will break or fracture.

Needless to say, it is recommended that the worker cut the bars and arrange them

separately, as depicted below.

tension fixed lengthtension fixed

length

breakable due to the tension

Wrong method Correct method

Page 7: Design Details

7) Hunch beam① Bend the bars at the bottom in a hunch former and anchor them onto the pillar.

② Bend a half of the bars at the bottom to let the anchorage length penetrate the pillar

and anchor near the hunch point.

③ One size bigger stirrup should be used at the hunch point.

8) Pillar-holding rebar (Butterfly stitching rebar/Stirrup closing rebar)① As few drawing gives direction on pillar-holding rebar, it is common to use it at

every third stirrup.

If not, all junctions of pillar-holding rebar should be confined per every stirrup.

S.T. one size bigger stirrup

stirrup

processing

(current) (revised)

<butterfly stitching rebar>

Better if one end hooked 135°

Page 8: Design Details

9) Symbol of beam·Continuous end of beam

·Center of beam

·Exterior of beam

·Interior of beam

·Outside of beam

end stirrup:arrange 200mm distance-D10upper part : HD22-3

end top bar : HD22-2

EXT(exterior) CENT(center)

400×500(stirrup process size : 320×420)

300×500(stirrup process size : 220×420)

stirrup : arrange 200mm distance-D10

tension splice(B class splice)

upper part bar : HD22-3EA

END(end)

END(end) CENT(center)

center stirrup-arrange 250mm distance-D10

center top bar : HD22-2

lower part bar :HD22-3

support bar : HD13-2EA

support bar : HD22-3EA

lower part bar : HD22-3EA

Page 9: Design Details

10) Detailed drawing of beam rahmen(arrangement)

horizontal rebar : HD10@200(arrange 200mm distance-D10)

vertical rebar : HD10@200(arrange 200mm distance-D10)

400×500(stirrup process size : 320×420)

400×400(hoop process size : 320×320)

tension splice(B class splice)

Each floor bottom structure plane figure symbol & beam chart symbol

END(end) CENT(center)

tension splice

hoop : arrange 250mm distance-D10

main bar : 10-HD19

support big bar : arrange 250mm distance-D10

Page 10: Design Details

※ You should check pillar size & rebar Q’ty per each floor, and also arrange after

checking rebar Q’ty & drawing of outer pillar’s front and side.