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For Purlins and Sagrods: 1.49 KG/M 1kN 1000 N 47.88 N /M 1lb/ft 1kN 1000 N

The document summarizes the structural design of purlins and sagrods for a roof with a span of 0.96m. It calculates loads, properties of a trial C4X7.25 section, and checks if the section is supported, partially supported, or unsupported. The calculations determine the section is partially supported. It then calculates the design bending moment capacity and verifies the section is safe. For sagrods, it calculates the maximum tensile force and determines a 13.75mm diameter satisfies the design requirement.

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Joshua Balleon
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89 views3 pages

For Purlins and Sagrods: 1.49 KG/M 1kN 1000 N 47.88 N /M 1lb/ft 1kN 1000 N

The document summarizes the structural design of purlins and sagrods for a roof with a span of 0.96m. It calculates loads, properties of a trial C4X7.25 section, and checks if the section is supported, partially supported, or unsupported. The calculations determine the section is partially supported. It then calculates the design bending moment capacity and verifies the section is safe. For sagrods, it calculates the maximum tensile force and determines a 13.75mm diameter satisfies the design requirement.

Uploaded by

Joshua Balleon
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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FOR PURLINS AND SAGRODS

Purlin Spacing=0.96m
No. of Purlins= 16

Trial Section: C4X7.25


Properties:
bf= 1.72 rx= 1.47 Iy= 0.433
tf= 0.296 ry= 0.447 bo= 1.584
tw= 0.321 d= 4 ho= 3.704
Sx= 2.29 Zy= 0.695 W= 7.25lb/ft
Sy= 0.337 Zx= 2.84

DEAD LOAD:
1.49 kg/m 1 kN
Purlin weight= 7.25lb/ft ( ) (9.81m/s²) ( )=0.1058 kN/m
lb/ft 1000 N
47.88 N /m ² 1 kN
Roofing: (Galvanized Steel Gauge 20) = 1.656lb/ft² ( )( ) (0.96)= 0.076kN/m
1 lb/ft 1000 N
Total Dead Load= 0.1818kN/m

LIVE LOAD: 0.75 kPa (0.96)= 0.72 kN/m  Table 205-3 (NSCP, 2015)
WIND LOAD: 2.43kN/m²(0.96)=2.33kN/m

Using Load Combination: 1.2D+1.6L+0.5W


Gravity Load= 1.2(0.1818)+1.6(0.72)=1.37kN/m
Wind Load= 0.5(2.33)=1.165kN/m
Resolving into Components:
Wn= GLcosƟ+WL
=1.37cos(2.7)+1.65=2.39kN/m
Wt= GLsinƟ
=¿)sin(27)= 0.62kN/m

WnL ² 2.39(5)²
Mux= = = 7.27kN/m
8 8
5
Wt L ² 0.63( ) ²
Muy= = 3 = 0.17kN/m
10
10

Check if Supported, Partially Supported, or Unsupported


L
Lb= = 1.67m or 65.75in
3

Lp= 1.76 ry
√ fY √
E = 1.76(0.447) 29000 = 22.32 in
36

Lr= 1.95rts
E
0.7 fy √ √ √
Jc
Sxho
1+ 1+6.76 (
0.7 fySxho
Ejc
¿ ¿)² ¿ ¿

Jyho
rts= = 0.433∈ ⁴ ¿ ¿=0.35
2 Sx
3 3
2bo +f + ho+w ³ 2 ( 1.584 )( 0.296 ) + 3.704(0.321)
J= = = 0.0682in.
3 3

C=
3.7
2 √ 0.433 = 1.09
1.24

Lr= 1.95(0.35)(
29000
36(0.7)
)
√0.0682(1.09)
2.29(3,7)
√ 1+ √1+6.76 ¿ ¿ ¿)² = 73.57
Lp<Lb< Lr ; Section is Partially Supported
Lb−Lp
Use: Mn= Cb[Mp-(Mp-0.7FySx)( )]
Lr−Lp
Mp= FyZx= 248.211(72.136X10³)= 17.9 kN-m
1225 (1200)
Cb= =1.32
2.5 (1200 )+3 ( 600 )+ 4 ( 1200 ) +3(600)

67.75−22.32
Mn= 1.32[17.9-(17.9- 0.7(36)(2.29)( )]≤Mp
73.53−22.32
= 66.83kNm ≤Mp
Use Mn= Mp= 17.9 kNm
Mpy= FyZy= 36(0.695)= 2.83kNm<1.6FySy
=1.6(36)(0.337)
=19.4  OK
Checking the Section:
Mux Muy
+ ≤1.0
ƟbMnx ƟMny
7.47 0.17
= + =0.19<1
0.9 ( 66.83 ) 0.9 ( 2.83 )
Therefore, C4X7.25 is SAFE

Sagrods: Grade 33 Steel


5 5
Tsag= W+L= (0.62)(5)= 1.94kN
8 8
Tsagmax= 1.94(5)=9.7kN
ƟpN≥Pu
0.9(Fy)(Ag)≥Pu
∏d²
0.9(33x6.9)( )= 9.7x10³
4

d=
√ 9.7 x 10³ (4)
0.9(33 x 6.9)
d= 13.75 mm
L
Therefore, use 13.75mm Sagrods at spacing
3

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