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Wind Load Calculation

This document provides load calculations for the design of cold formed thin gauge roof truss sections according to BS5950 Part 5. It lists dead loads, live loads, and wind loads to consider. Dead loads include metal roofing, purlins, and truss self weight. Live load is specified as 0.25 kN/m^2. Wind load calculations determine pressure coefficients for different wind angles and surfaces. Several load combinations are also provided to consider for structural analysis and design.

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Ah Chia
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653 views3 pages

Wind Load Calculation

This document provides load calculations for the design of cold formed thin gauge roof truss sections according to BS5950 Part 5. It lists dead loads, live loads, and wind loads to consider. Dead loads include metal roofing, purlins, and truss self weight. Live load is specified as 0.25 kN/m^2. Wind load calculations determine pressure coefficients for different wind angles and surfaces. Several load combinations are also provided to consider for structural analysis and design.

Uploaded by

Ah Chia
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLSX, PDF, TXT or read online on Scribd
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BS5950 Part 5: Code of Practice for Design of Cold Formed Thin Gauge Sections

LOADINGS FOR ROOF TRUSS


1) DEAD LOADS Reference

Metal Roofing + Insulation = 0.064 kN/m2


Purlins Self Weight = 0.15 kN/m
Truss Self Weight = 0.06545 kN/m2
Ceiling Self Weight + Services = 0.26 kN/m2

2 ) LIVE LOAD

Live Load (Imposed Load) = 0.25 m/s kN/m2 Uniform Building By-laws 1984, Part V
Clause 63 (5) (a)
3 ) WIND LOAD

Basic wind speed, Vo = 40 m/s


Topography Factor, S1 = 1
Statistical Factor, S3 = 1
Wind Direction Factor,S4 = 1

Factor S2

From Table 3,
Height H≤ 15.0 m,
S2 = 1

The dynamic pressure q, corresponding to this design wind speed is given as: CP3: Chapter V: Part 2, 1972 P.13
q = 0.613Vs2

where Vs = V0*S1*S2*S3*S4 m/s


= 40 m/s

Therefore, q= 980.8 N/m2

Height to width ratio 1/2 < h/w ≤ 3/2 CP3: Chapter V: Part 2, 1972
Table 8, P.19
Roof pitch = 5 degree

For wind angle a = 0o CP3: Chapter V: Part 2, 1972


Table 8, P.19

Cpe for windward side = -0.45


} CASE A
Cpe for leeward side = -0.5

For wind angle a = 90o CP3: Chapter V: Part 2, 1972


Table 8, P.19
Cpe for windward side = -0.8
} CASE B
} CASE B
Cpe for leeward side = -0.7

Cpi = -0.3 for approximately equal permeability CP3: Chapter V: Part 2, 1972
Appendix E, P.42
F = (Cpe - Cpi)qA CP3: Chapter V: Part 2, 1972
Clause 7.2
CASE A:

Windward: F= -0.1471 kN/m2


Leeward: F= -0.1962 kN/m2

CASE B:

Windward: F= -0.4904 kN/m2


Leeward: F= -0.3923 kN/m2

4) LOAD CASE

Loadings on TOP CHORD = Point loads from purlins

Span of purlin = 1.800 m

Load width of purlin= 1.200 m

A ) POINT LOADS Reference

Dead Loads (DL) = 0.4596 kN

Live Loads (LL) = 0.5400 kN

Wind Loads (WL) = -1.0593 kN (Note: +ve is downward)

Therefore:
Wind Load (â) = 0.0000 kN

Wind Load (á) = -1.0593 kN

B ) LOAD COMBINATIONS
Load cases to consider:
Case 1: 1.0G
Case 2: 1.0Q
Case 3: 1.0Ws
Case 4: 1.4G + 1.6Q
Case 5: G + 1.4Wu
Case 6: 1.4G + 1.6P

where :
G= Gravity load or dead load
Q= Live load or short term load
Ws= Wind serviceability load downwards
Wu = wind load upwards
wd = wind load downwards
P= 1.1 kN applied mid span

CASE 1:
1.0G = 0.7280 kN/m2

CASE 2:
1.0Q = 0.2820 kN/m2

CASE 3:
1.0Ws = 0.0000 kN/m2

CASE 4:
1.4G + 1.6Q = 0.5050 kN/m2

CASE 5:
G + 1.4Wu = 0.0360 kN/m2

CASE 6:
1.4G + 1.6P = 2.7790 kN/m2

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