16. Calculation of beam rebar

Bent bar that is placed above(up) and below(down) of beam is Main-Bend, and bent

bar that is placed on both sides of beam is Side-Bend.

Main-Bend

※ Hunch angle should not exceed 45°(bent angle is "bent angle")

Side-Bend

Calculation of all 2 types of bent bar is the same except the way of extracting pure

height of main bar from stirrup height(thickness).

Either span of , from one end can be accepted depending on their uses.

1) Calculation of up-down bend(Main-Bend) in the beamProvided that the height of beam is 500mm , the length of span is 8,000mm and the

size of pillar is 500mm , then the steel requirement is as follows.

① 8,000mm-(500mm-40mm-40mm)-(500mm-40mm-40mm)=7,160mm

7,160mm÷4=1,790mm Hence, the value of ① is 1,790mm

beam height ST height

100 cover

inner length left rightup·down cover up·down cover

② 1,790mm×2=3,580mm(value of ②) are extracted hunch length from inner length

③ Extract cover depth from 500mm(beam height : 420mm) and multiply this by 1.4,

and again extract 20mm(D10 diameter), [500mm - (40mm×2)]×1.4 - 20mm =

568mm, and then we have 568mm.

※※ Calculation of hunchHunch = the height of stirrup×1.4 - 20(bar diameter of top and bottom stirrup×2)

④ fixed length is 40d in usual, hence provided that used bar is HD19,19mm×40d=760mm

The length of anchor ⑥ is 760mm- pillar fixation 400mm=360mm

⑤ 400mm + ① 1,790mm = 2,190mm

⑥ 400mm is the rest value except cover 100mm from width of pillar.

The length indication when spreading above calculation is as follows.

※ Total length 9,806mm for 8,000mm bar, the splice length is 2,566mm.

(example) 9,806mm-8,000mm=1,806mm, Total length is 1,806mm+760mm(splice

length)=2,566mm

2) Calculation of side bend in the both sides of beam

beam height 280(ST height)

actual height

END CENTER

100 cover

① 8,000mm - (420mm - 70mm - 70mm) - (420mm - 70mm - 70mm) = 7,440mm,

that is, 8,000mm - (280mm×2) = 7,440mm, and then 7,440mm× = 2,232mm.

② Center point is , and then 7,440mm× = 2,976mm.

③ Hunch length is calculated from hunch height multiply 1.4.

280mm×1.4 = 392mm, hence hunch length is 392mm.

④ Fixed length is 40d in usual, hence provided that used bar is HD19, 19mm×40d =

760mm is fixed length , 760mm - 400mm(pillar fixed) = 360mm(anchor value⑥)

value① 2,232mm + 400mm = 2,632mm(actual distance of end upper part)

⑤ Cover depth(100mm) is extracted from pillar size(500mm)

500mm - 100mm = 400mm

If the bent bar mentioned so far is straightened in a line, it is like shown below.

※ Total length required is 9,744mm and provided that the standard bar length is

8,000mm, we need to splice here and the splice length is 2,504mm.

example)

9,744mm - 8,000mm = 1,744mm

1,744mm + 760mm(splice length) = 2,504mm(total length)

※ To summarize, Main-Bend's return bend point is lx point, Side-Bend is lx

point, you can find the bending to exterior side(to center part).

inner length ST height left right(up·down distance)

side-bend height

totallength