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DESIGN CALCULATIONS FOR THE RECTANGULAR SHADE STRUCTURE
I. General
1. Design PhilosophyThe purpose of this calculation is to design
the shade structure for its integrity, strength
and stability verification. The result of this conclusion is
that the structure considered
adequate in meeting the required of design criteria.
2. Unit of Measurement
Unit of measurement in design shall be in Metric system.
II. Design Calculations
1. Design Code and reference:
BS 5950: Structural use of Steel. Code of practice for steel
design
BS 8110: Structural use of Concrete. Code of practice for
concrete designWind loads as per CP3
STAAD Structural Program for calculations.
2. Materials
Steel Columns - Pipes of OD 168mm with 4mm thick
Horizontal, Curved and Connecting members,Steel Pipes of OD 60mm
with 3.2mm thick
Small Vertical Pipe of OD 48mm with 3.2mm thick
The modulus of elasticity of steel E = 210000 N/mm2Ultimate
Bending stress steel Po - = 275 MPa = 275 N/mm
2
Ultimate Tensile Stress steel Pa = 435 MPa = 435 N/mm
2
Ultimate Shear Stress steel Pv = 0.6X Po = 0.6X275 = 165 MPa =
165 N/mm2
All bolts used shall be grade 8.8 or high yield.
3. Loading
Dead Load Self weight is considered
Dead Load Fabric Load (350 gm/Sqm)
Wind loads (WL) calculated as per CP3: ch.V
The canopy is located at a height of 3.0m.
Basic wind speed assumed as 45 m/s.
Basic wind speed V = 45.0 m/sec
Design wind speed Vs = V x S1 x S2 x S3
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Where,
Topography factor, S1 = 1.0
For the calculation of S2, ground roughness, building size and
height above ground,
factor S2 = 0.74, as per CP3: Chapter V: Part 2, Clause 3
(Country with many windbreaks; small towns; outskirts of large
cities), class C for 10m average height.
Statistical factor, S3 = 1.0
Design wind speed Vs = 45.0 x 1.0 x 0.74 x 1.0
Design wind speed Vs = 33.3 m/sec
Wind pressure q = k Vs2
K constant = 0.613
Wind pressure q = 0.613 x (33.3)2
Wind pressure q = 680 N/m2 or 0.68 KN/m2
Wind Pressure q = 0.68 KN/m2
The maximum and minimum pressure co-efficients are,
Cp = +0.7, and -0.7,
Net wind uplift Pressure = Cp X q
Net wind uplift Pressure = -0.70 X 0.68 = 0.476 KN/m2
Net wind Pressure = Cp X q
Net wind Pressure q = 0.70 x 0.68 = 0.476 KN/m2
4. Load Combinations
Design & Ultimate factors are considered.
as per BS standard,
UL = 1.40 DL + 1.4 WL
UL = 1.0 DL + 0.8 WL
5. Design Method
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The shade structure with a span of 8.0m and width is considered
and as shown and the
average centre to centre spacing between the pipes is considered
as 8.0m.
Loads are calculated on the spacing between the structures which
are as follows:
Dead Loads:
a) Self Weight to be checked from the program
Dead Load = 0.035 X 8.0 = 0.28 KN/m
Wind Loads:
a) Uplift wind load = 0.476 X 8.0 = 3.81 KN/m
b) Downward wind load = 0.476 X 8.0 = 3.81KN/m
To check the maximum length of the canopy structure against all
the above loadingcombination and to be on factor of safety (see
attached calculations made by the
structural program STAADPRO).
6. Conclusion:
All the materials used in the shade structure for all spans are
structurally sufficient andmeets its intended purpose.
