DESIGN CALCULATIONS FOR THE UMBRELLA CAR PARK SHADE STRUCTURE I.
General 1. Design Philosophy The purpose of this calculation is to design the car park 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: Chapter V. Loading part 2 – Wind loads American Standards STAAD – Structural Program for calculations. 2. Materials Steel tubes of OD 168.3mm with 6.3mm thick Steel tubes of OD 76.0mm with 4mm thick Steel tubes of OD 60.3mm with 3.6mm thick The modulus of elasticity of steel – E = 210000 N/mm2 Ultimate Tensile stress – 275 N/mm2 All Chemical anchors used shall be “HILTI” or equivalent. All bolts used for main connections shall be grade 8.8 or high yield. 3. Loading Dead Load – Self weight is considered Dead Load – Fabric Load (830 gm/Sqm) Wind loads (WL) calculated as per CP3: ch.V The carpark shade structure is located at a height of less than 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 Where, Topography factor, S1 = 1.0
For the calculation of S2, ground roughness, building size and height above ground, factor S2 = 0.6, as per CP3: Chapter V: Part 2, Clause 3 (Country with many breaks; outskirts of large cities), class B for less than 3m average height. Statistical factor, S3 = 1.0 Design wind speed Vs = 45.0 x 1.0 x 0.6 x 1.0 Design wind speed Vs = 27.0 m/sec Wind pressure q = k Vs2 K – constant = 0.613 Wind pressure q = 0.613 x (27)2 Wind pressure q = 447 N/m2 or 0.45 KN/m2 The maximum pressure co-efficients are, Cp = +0.2, and -0.5, Net wind Pressure = Cp X q Net wind Pressure q = 0.2 x 0.45 = 0.09 KN/m2 Net wind Pressure q = -0.5 x 0.45 = -0.225 KN/m2 4. Load Combinations Design & Ultimate factors are considered. As per UBC 1982 Edition, UL = 0.9 DL + 1.3 WL 5. Design Method The cantilevered unipole car park shade structure is 5.50m X 5.50m with diagonals connecting at the centre. The maximum clear span in the middle portion will be 3.90 m length as shown and the loading should be calculated for a distance of 2.75m width. Dead Loads Self weight is considered from the Program itself. Fabric Load to be calculated as follows,
Fabric Load = 0.83 X 2.75 = 2.28 Kgs/m = 0.023 KN/m Wind load on the structure = 0.09 X 2.75 = 0.25 KN/m Wind load on the structure = -0.225 X 2.75 = -0.62 KN/m 6. Conclusion: All the materials used in the cantilevered car park shade structure for all spans are structurally sufficient and meets its intended purpose.
