calculation note roof truss design.pdf

8/13/2019 Calculation Note Roof Truss Design.pdf

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Project: Warehouse Calculation Note

I. (DESIGN STANDARD AND SPECIFICATION )

1.1 (Design Criteria)

AISCThe design criteria for steel structures shall be conformed to AISC Specification.

ASCEAll design load and wind load calculation method on the building shall be conformed to ASCE.

1.2 (Design Codes and Specification)

Generally, Codes and Standards are complied with international standards.

The codes and standards adopted are listed below:

- AISC 360-05 - AISC 360-05 for Structural Steel Design

- ASTM - ASTM SPECIFICATION for Materails use

- AWS - AWS for Structural Welding Code-Steel

- ASCE 7-05

- ASCE 7-05 for Minimum Design Loads on Structures

- IBC 2009 / ASCE 7-05 - IBC 2009 / ASCE 7-05 for Load Combination

1.3 (Materials)

The materials used in the structures and accessories shall be conformed to the following:

-

(structural member) ASTM A36M or Equivalent

- (steel plate) ASTM A36M or Equivalent

- (bolt) ASTM A325M or Equivalent- (Nut) ASTM A325M or Equivalent- (spring washer) ASTM A436 or Equivalent

Calculated by: SOK RASMEY, MEng. ETC Page-1-


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:

: ASTM

:



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: 1.4 (Load Factor and Load Combination)

AISC ASCE 7 (ASEC 2005) LRFD (Load and Resistance Factor Design)

U 1 4 D F =

U 1 2 D F T 1 6 L H 5 L r S R =U 1 2D 1 6W 1 L 5 L r S R =U 1 2D 1 E 1 L 2S=

U 9D 1 6W 1 6H =

U 9D 1 E 1 6H =

D =

E = F = H =

T = L = Lr = W = S = R =

1.5 (Strength Reduction or Resistance Factors)

1.0 AISC



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II. (DESIGN OF ROOF TRUSS)

2.1 (Geometric Roof Truss)

: 2D

: 3DCalculated by: SOK RASMEY, MEng. ETC Page-4-


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(Truss spacing) S 6 25m

(Length of truss) L 3 m

(Truss height) h 1 5m

(Roof height) H 3 m

(Slop angle) atan H 5L

11 31 deg

(Number of panel) n 2

(Length of panel) dL

n cos 1 53 m

2.2 (Load on Roof Truss)

2.2.1 (Weigth of Structural and roof materials)

(Wiegth of top and bottom chord)

w2L4x4x1 3125 24 4 5kgfm

(Wiegth of diagonal member)

w2L2 52 51 1875 9 137kgfm

(Wiegth of vertical member)

w2L2 52 51 1875 9 137kgfm

(Wiegth of bracing)

wL3x3x 1875 1 6kgfm

(Wiegth of purlin)

wC15 753 2 7 37kgfm

2.2.2 (Design load)

(steel sheet and insulation)

Sheet 15kN

m2

(Suspended ceiling & Mechanical)

Ceiling 4kN

m2

(Roof live load) Lr 5kN

m2

(Wind load) Wind 5kN

m2

- (Load on joint/concentrated load )



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(Tributary area) AT S d 9 561 m2

1. (Dead)

PDL Sheet A T Ceiling A T cos 5 184 kN

2. (Roof live)

PLr Lr AT cos 4 688 kN

3. (Wind)

Pw Wind AT 4 78 kN

(Robot) 2.2.3 (Axial Force)i. (Lower Chord)

(Dead): NDL 22 59 kN 65 75 kN 88 34 kN

(Roof live): NLr 59 46kNNw 6 62kN (Wind):

(Combination):

Nu1 1 4N DL 123 676 kN

Nu2 1 2 N DL 5 N Lr 135 738 kN

Nu3 1 2N DL 1 6N w 5N Lr 232 73 kN

Nbot max Nu1 Nu2 Nu3 232 73 kNii. (Upper Chord)

(Dead): PDL 47 37 kN 132 9 kN 179 46 kN

(Roof live): PLr 119 46kNPw 121 8 kN (Wind):

(Combination):

Pu1 1 4P DL 251 244 kN

Pu2 1 2 P DL 5 P Lr 275 82 kN



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Pu3 1 2P DL 1 6P w 5P Lr 469 962 kN

Ptop max Pu1 Pu2 Pu3 469 962 kN

iii. (Diagonal)

(Dead): NDL 14 71 kN 43 99 kN 58 7 kN

(Roof live): NLr 39 78kNNw 4 56kN (Wind):

(Combination):

Nu1 1 4N DL 82 18 kN

Nu2 1 2 N DL 5 N Lr 9 33 kN

Nu3 1 2N DL 1 6N w 5N Lr 155 226 kN

Ndia max Nu1 Nu2 Nu3 155 226 kNiv. (Post / Vertical Web)

(Dead): PDL 11 89 kN 36 94 kN 48 83 kN

(Roof live): PLr 33 41kNPw 34 6kN (Wind):

(Combination):

Pu1 1 4P DL 68 362 kN

Pu2 1 2 P DL 5 P Lr 75 3 1 kN

Pu3 1 2P DL 1 6P w 5P Lr 129 797 kN

Ppost max Pu1 Pu2 Pu3 129 797 kN (Result from analysis)

Axial force in top chord Pt Ptop 469 962 kN

Axial force in bottom chord P b Nbot 232 73 kN

Axial force in post member P p Ppost 129 797 kN



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Axial force in diagonal member P d Ndia 155 226 kN

2.3 (Design of Truss Members)

Steel yield strength F y 36ksi 248 211 MPa

Modulus of elasticity of steel E 2 15

MPa

2.3.1 (Design of Upper Chord)Factored load P u Pt 469 962 kN

Length of member L d 1 53 m

For section 2L 102x102x7.9 Imin 3 13 16

mm4

Ag 31 mm2

rIminAg

31 775 mm

Effective length factor K 1

Slenderness ratio K L

r48 141

K Lr

2 , OK

Slenderness parameter cK Lr

FyE 54

Critical buckling stress

Fcr 658 c 2 Fy c 1 5f

877

c2

Fy otherwise

Fcr 219 7 9 MPa

Resistance factor for compressive members c 85

Nominal compression strength P n Ag Fcr 681 98 kN



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Safety factor FSPu

c Pn 812

2.3.2 (Design of Lower Chord)

Factored force P u Pb 232 73 kN

Length of member L d 1 53 m

For section 2L 76x76x6.4 Ag 185 mm2

Resistance factor for tensile member t 9

Nominal strength P n Fy Ag 459 191 kN

Safety factor FSPu

t Pn 563

2.3.3 (Design of Diagonal)

Factored force P u Pd 155 226 kN

For section 2L 64x64x4.8 Ag 116 mm2

Resistance factor for tensile member t 9

Nominal strength P n Fy Ag 287 925 kN

Safety factor FSPu

t Pn 599

2.3.4 (Design of Post)

Factored load Pu Pp 129 797 kN

Length of member L 1 5m

For section 2L 64x64x4.8 Imin 466 16

mm4

Ag 116 mm2

rIminAg

2 43 mm



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x2x1 x2

72 P 1x2

x1 x2 P u 169 2 9 kN

x1x1 x2

28 P 2x1

x1 x2 P u 65 772 kN

Lengths of welds

L1 maxP1

7 7 w F w 4 w

297 6 4 mm

L1w

49 6 1

L2 maxP2

7 7 w F w 4 w

115 679 mm

L2w

19 28

Lower Chord

Weld size w 5mm

Centroid of section 102x102x7.9 x1 28 55mm

x2 1 2mm x 1 73 45 mm

Factored load P u

Pb2 116 365 kN

x2x1 x2

72 P 1x2

x1 x2 Pu 83 794 kN

x1x1 x2

28 P 2x1

x1 x2 Pu 32 571 kN

Lengths of welds

L1 maxP1

7 7 w F w 4 w

176 852 mm

L1w

35 37

L2 maxP2

7 7 w F w 4 w

68 742 mm

L2w

13 748

Diagonal Member

Weld size w 3mm



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Centroid of section L64x64x4.8 x1 17 645 mm

x2 64mm x 1 46 355 mm

Factored load P uPd

277 613 kN

x2x1 x2

724 P 1x2

x1 x2 P u 56 215 kN

x1x1 x2

276 P 2x1

x1 x2 P u 21 398 kN

Lengths of welds

L1 maxP1

7 7 w F w 4 w

197 74 mmL1w

65 913

L2 maxP2

7 7 w F w 4 w

75 27 mm

L2w

25 9

Post Member

Centroid of section L64x64x4.8 x1 17 645 mm

x2 64mm x 1 46 355 mm

Factored load P uPp2

64 898 kN

x2x1 x2

724 P 1x2

x1 x2 P u 47 6 kN

x1x1 x2 276 P 2

x1x1 x2 P u 17 893 kN

Lengths of welds

L1 maxP1

7 7 w F w 4 w

165 347 mm

L1w

55 116

L2

maxP2

7 7 w F w 4 w

62 939 mm

L2

w2 98


calculation note roof truss design.pdf

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