Ref
Calculations
Classification : Brace non-slender column
Design the longitudal and transverse reinforcement for the column shown
below. The column are objected to 50 years working life, 1 hour fire
resistance and build inside building. Use grade C25 concrete and grade
500 steel reinforcement.
Specification
Concrete, fck = 25 N/mm2
Reinforcement, fyk = 500 N/mm2
Exposure class = XC1
Fire Resistance = 1.0 hours
Design life = 50 years
Size, b X h = 350mm x 450mm
Effective length, l0 = 3800mm
Assumed : link = 8 mm
bar = 20 mm
Axial force, Ned = 2200 kN
Durability, Bond & Fire Resistance
Table 4.2
Min.cover with regard to bond, Cmin,b = 20mm
Table 4.4N
Min.cover with regard to durability, Cmin,dur = 15mm
Min.required axis distance for R60 fire resistance
Table 5.2A
Resistance sd = 40 mm
Min.concrete cover with regard to fire,
Cmin = sd - link - bar/2
= 40 - 8 - (20/2)
= 22 mm
4.4.13
Allowance in design for deviation, C dev = 10 mm
Output
4.4.1.4 (2)
Nominal Cover
Cnom = Cmin + C dev
= 22 + 10
= 32 mm
5.8.8.2
Design Moment
For non-slender column the design moment,
Med = Max ( Mo2 , M min ) (choose highest )
Where,
Mo2 = M = Ned, ei
M = max ( M bot , M top ) = 55 kNm
5.2 (7)
ei = ( lo/ 400) = 3800/400 = 9.5mm
Mo2 = 55 + ( 2200 x 0.0095 ) = 75.90 kNm
6.1 (4)
M min = Ned, eo
eo = h/30 20 mm
= 450/30 = 15 mm
= 15 < 20 mm ( use 20mm) @ 0.02
M min = 2200 x 0.02 = 44 kNm
Mo2 > Min
75.90 > 44
Med = 75.90 kNm
Use :
Cnom = 35mm
Reinforcement
d2 = Cnom + link + bar/2
= 35 + 8 + 10
= 53 mm
d2 /h = 53/450
= 0.12
Refer
Design
Chart
9.5.2 (2)
NEd/bh x fck = 2200 x 103 / 350 x 450 x 25
= 0.56
MEd/bh2 x fck = 75.90 x 106 / 350 x 4502 x 25
= 0.04
As x fyk / bh x fck = 0.09
As = 0.09 bh x fck / fyk
= 0.09 (350 x 450) (25) / 500
= 708.75 mm2
Use 2H20 (628 mm)
(+)
2H12 (226 mm)
= (854 mm)
9.5.2 (2)
As,min = 0.1 Ned /fyk(0.87)
= 0.1 (2200 x 103) /(500x0.87)
= 506 mm2 or 0.002 Ac = 315 mm2
9.5.2 9 (3)
As,max = 0.04 Ac
= 0.04 x 350 x 450
= 6300 mm2
Use : 506
Proven : As min < As prov < As max
OK!
500 mm2 < 854 mm2 < 6000 mm2
9.5.3
Links, min = 0.25 x the larger of bar
Use: link
H8
= 0.25 x 20
= 5 mm or 6 mm
Sv max = 20 x the lesser of bar
= 20 (12)
= 240 or 350 or 400
use H8 - 200
At section 300 mm below & above beam and at lapped joints ,
Sv max = 0.6 x 200
= 120
Use H8-100
Bengkok Link @ Link Tambahan
35
280
35
35
380
35
1) 350 2(35) - bar 2(link bar)
= 350 70 20 2 (8)
= 244 mm
2) 450 2(35) - bar 2(link bar)
= 450 70 10 - 6 2(8)
= 348mm
3) 350- 2(35) - bar 2(link bar)
=350 70 12 16
= 252mm
Tambatan Tetulang
= (244 + 348 + 348 + 252) + 2(2 r bar) + 2(2 r bar) + 2(4 link)
= 1192 + 2(2 (10))+ 2(2 (6)) + 64
= 1192 + 62.83 + 37.7 + 64
= 1.36m
Bilangan Tetulang
Lapping = (h / b) + 1
(450/350) + 1 = 2.29 ~ 3 batang
Panjang tiang - overlapping
3800 600 = 3200
3200 / h = 3200/450 =7.1 ~ 8 batang
3 + 8 = 11 nos
Anggaran Bahan
Jumlah link
= 1.36m 11nos
= 14.96+ 3% pembaziran =15.41
=15.41/12 = 1.28 ~ 2 batang (H8)
Besi tetulang
(H20)
= 3.8m 2btg
= 7.6 / 12 = 0.63 batang + 3% pembaziran
= 0.65
(H12)
= 7.6 / 12 = 0.63 batang + 3% pembaziran
= 0.65
Konkrit
Lhb
= 3.8 0.45 0.35
= 0.6m3 + 5% pembaziran
= 0.63m3
Drawing
