10. Calculation of the quantity of Rebar material

Transcription

1 10. Calculation of the quantity of Rebar material 1) Extra of rebar In case of deformed bar, extra is 3% in general when including fixed & splice length of rebar, however, it is proportional to bar size. 16mm or larger : more than 5% extra 3% of 100ton is = 3ton Rebar calculation included extra 3-8% after calculating fixing & splice. Therefore, those works will prevent from the reason of illegal construction practices with correct quantity & regular position carryout of construction by calculating bar-list with shop drawing. If rebar will be processed in rebar processing factory, basically extra is as follows. In construction work 3%, in engineering work 6%, support work 3~4%. You have to consider the economical efficiency and construction carryout efficiency in site after analyzing in advance about extra percentage per rebar size by the criterion per construction carryout area.

2 2) Base plate(footing) <Example : 1> <Example-1> In foundation, shown as above, requirement of bar includes 20pcs HD22 bars of 1,840mm (80(cover depth) 2(both ends) = 160mm is extracted from 2,000(original length of foundation), 2pcs D19 assist bars of 2,601mm(1,840) 1,414 ( 2 ), diagonal direction) and 4pcs short diagonal bars(2 bars in each diagonal direction) of 2,318mm(1,640(200mm is extracted from main bar length 1,840mm) 1,414 ( 2 ). HD22 1,840mm 20(foundation) = 36,800mm Weight = 36.8m(36,800mm) 3.04(unit weight) = kgf HD19 2,600mm(long bar) 2 = 5,200mm Weight = 5.20m(5,200mm) 2.25(unit weight) = kgf HD19 2,310mm(short bar) 4 = 9,240mm Weight = 9.24mm(9,240mm) 2.25(unit weight) = kgf Actual requirement of bar is HD22 = kgf HD19 = ( kgf kgf) = kgf LOSS(left bar strip) : The original length of bar before cutoff is usually 8,000mm. In case of above, 4pcs 1,840mm bars are produced and 640mm of bar strip is left. 5 bars are needed for foundation, hence = 3,200mm of bar strip is left. Its net weight is 3.20m(3,200mm) 3.04(unit weight) = kg. Actual requirement of bar is 8m 3.04(unit weight) 5 bars = kg

3 <Example : 2> What is the weight of D10 8m bar? 0.56kg 8m = kg How many D13 bars(8m criterion) in 2ton? 2,000kg ( kgx8m) = 251EA(standard is 240EA) Arrangement in foundation (base plate F) ( All the unit in drawing should be in 'mm') HD16 rebar 200mm space HD19 rebar 300mm space HD13 reinforcement bar 3EA HD16 = 2,000-(80(cover depth) 2(both ends)) = 1,840 (cutoff dimension) HD19 = 3,000-(80(cover depth) 2(both ends)) = 2,840 (cutoff dimension) HD13 = = = 3,383 (cutoff dimension) (Note. x = x x, 10 = = 100) Here, multiply unit weight and number, then net weight of bar is HD16 = 1.84m(1,840mm) kg = kg = = 15EA kg 15 = kg

4 HD19 = 2.84m kg = kg = = 7EA kg 7 = kg HD13 = 3.38m(3,380mm) 0.995kg = kg Weight = kg assist bar(3+3) = kg Among 6 assist bars, two(2) of them in 3,380mm and the other(4) in 12,320mm (4x3,080mm : 300mm shorter) Net weight is = kg and add 5% extra, hence kg is required.

5 3) Base(footing) and pillar As various footing types like continues footing, single footing and mat footing, there are many shapes of footing, that is, triangle, right triangle, square, rectangle, pentagon, circle, multi-layer plate, etc. In this book triangle shape footing and single reinforcement footing are dealt with. F1 plane cover50 HD19-6EA In case of footing shown left cover depth, the type of bar and the size of bar should be considered. In addition, the reinforcement at footing-pillar junction should be included here. Before bar cutoff, the size of C1, the area of main reinforcement, the size of hoop and the spacing of stirrup are all considered consulting the bar list. Section HD22-8EA cover80 upper part, lower Calculation : Footing shown left is in contact with soil, hence cover depth is 80mm at each end(80 2 = 160 at both ends). 160mm is extracted from footing length 2,000mm, and this(1,840mm) is divided with spacing 200mm. Then 10 reinforcement(at every 9 spacing +1 at the end) is required here. Now reinforcement is in two directions and therefore we need 20 reinforcements.

6 4) Pillar Similar to footing, there are many shapes of pillar, that is, triangle, right triangle, square, rectangle, pentagon. circle, etc. The worker is recommended to earn a lot of working experience. Calculation of pillar D10@300 D10@300 upper part, lower HD22-8EA In calculation, tie hoop, stirrup, main bars in column and the others should be included here. First extract cover depth from hoop size (400mm), and cover depth in the basement and above the ground should be different. Net length cover depth (40+40) = 320 (dimension) 4(4sides) 1, mm of hook then, cutoff length is 1,380mm. Since net length of hook is 100mm, only 100mm of extra length is added here. If the bar size is D10, one end is hooked in circular, so 2 times of bar diameter (20mm) is extracted here, As 5 hooks are needed and hook length is 100mm at each end(200mm in total), 80mm is extracted from 100mm. Then this 80mm is added to produce 200mm of hook length.

7 5) Calculation of main rebar If you will carry-out with 8,000mm rebar including both fixed length(anchor) from total length of 1 span, you just add the splice length from rebar diameter to use. Example) Total length 62,000mm + both fixed length(anchor) 1,000mm = Gross Total 63,000mm. When using HD19 rebar, splice length is 19 40d = 760mm. Rebar 8,000mm - splice length 760mm = 7,240mm. Gross Total 63,000mm 7,240mm = 8.7 piece (long bar 8piece & rest 5,080mm) Above splice length is 5,080mm including anchor. You can calculate it as above, but you have to carry-out the splice position as soon as closely by calculating several methods if spice position is not fit well. <Sample of processing> END CENTER long bar processing splice rebar long bar end top-bar center top-bar in span outside end end top-bar center top-bar in span outside end

8 6) Calculation of top rebar Please refer to the method in construction site as follows because it is very difficult to explain in theory. If 1 span is 8,000mm, 4,000mm will be center part and add 40times(40d) + rebar thickness is the length of top rebar in center part & end. You cut as 4,000mm +760mm = 4,760mm. When assembling current processing status, center part is from beam to upper part rebar splice position and end is lower part rebar splice position if splice rebar 2 pcs 4,580mm + long bar processed 1pc as upper part rebar and splice rebar 1pc 4,580mm + long bar processed 2pcs as lower part rebar will be used. And so, you assemble it mutually crossed and upper part is 2 bar from 3 bar from splice position. 7) Calculation of hoop If pillar size is width 400mm length 500mm, actual processing size is 320mm, 420mm except cover 40mm each(both 80mm). When processing hook by hand, it will be included 40mm from total length. When using Taeyeon's bending machine, it will be included 50mm from total length. coating thickness 40 process size Cut size : (420 2)+(320 2)+50 = 1,530mm Example of hoop usage : To avoid wrong bending of main bar and to restrict inner concrete, you maintain the space and no problem to assemble with 135 hoop at one side.

9 8) Calculation of stirrup If beam size is length 500mm, actual processing size is 420mm, 420mm except cover 40mm each(both 80mm). If beam size is width 300mm, actual processing size is 220mm, 220mm except cover 40mm each(both 80mm). Including hoop 50mm, you can use Taeyeon's bending machine. END CENTER Process size Cut size : (420 2)+(220+50(hook)=1,100mm Example of stirrup usage : To surround tension & compression bar and to restrict inner concrete, you maintain the space and bend with over 135 as stirrup end length. Taeyeon bending machine will be processed 90 or 135 with free by manufacturing of special tool & electric circuit. 9) Fact of processing According to rebar thickness and to bending angle, 2 times of rebar thickness will be used because of bending by circle of bending part than the length per actual straight line. <Tolerance of rebar process size> Drawing Item Symbol Tolerance( ) stirrup, tie hoop A, B 5 main bar below HD25 over HD29 A, B A, B length after processing - 20

10 10) Changed size if it bent 1 angle per specification When bending 1 angle, rebar D10 will be increased by 2cm each. When bending 1 angle, rebar D13 will be increased by 2cm each. When bending 1 angle, rebar D16 will be increased by 3cm each. When bending 1 angle, rebar D22~25 will be increased by 5~6cm each. Because bending part will be bent like R type, rebar will be less used per rebar diameter. Regarding processed rebar, it will be less used also by measuring with outside diameter size. If actual cut size is D10, (42 2)+(32+8(hook)) = 124cm Note) Process size must be outside diameter size of processed rebar. 11) Tolerance of processed size processed size Item stirrup, tie hoop, spiral rebar under D25 of deformed bar others D19~D41 of deformed bar total length after processing Tolerance( )