Structures load calculations shelters

Vigyan Ashram, Pabal

Why should you know how to Why should you know how to design a structure?design a structure?

Step 1 – What is the load on the Step 1 – What is the load on the structure?structure?

1) Dead Load Self weight Static loads

2) Dynamic Load Wind Rain People Loading/Unloading

Tractor ShedTractor Shed10m

4m

9m

5m

Truss

Column

Foundations

Dead LoadDead LoadSelf weight

Golden Rule:Work top to bottom

1. Truss

2. Column

3. Foundations

1. Load on Truss1. Load on Truss10m

4m

Steel Sheet – 10kg/m2

Mass 1 Truss – 100kg

Area of roof (m2) = x x

10 m 4 m 2 = 80 m2

Mass of roof (kg) = x

Weight of roof (N) = x

=

=

80 m2 10 kg/m2 800 kg

800 kg 10 8000 N

Weight of 1 truss (N) = x


4m



100 kg 10

8000N

= 1000 N

Total weight on trusses (N) = +


4m



3000 N

8000N

= 11,000 N

1000 N 1000 N 1000 N

8000 N

ActivityActivity How much roof weight must your structure support?

Plastic Sheet – 4.5 kg/m2

Mass 2’ PVC Pipe – 0.75 kg/m

Mass bamboo 1’ – 0.2 kg/m

Mass steel pipe 0.5’ – 0.36 kg/m


Mass steel pipe 1’ – 0.75 kg/m

Area of roof (m2) = x x

Mass of roof (kg) = x

Weight of roof (N) = x

10 m 4 m 2

=

=

=

80 m2

80 m2 10 kg/m2

800 kg

800 kg 10

8000 NWeight of 1 truss (N) = x100 kg 10

= 1000 NTotal weight on trusses (N) = + 3000 N

= 11,000 N8000 N

2. Load on Column. Load on Column

5m

Mass 1 Column – 10 kg/m

8000N

1000 N 1000 N 1000 N

Mass 1 pole = x

Weight 1 pole = x

=

=

50 kg

5m 10kg/m 50kg

500 N

10

2. Load on Column. Load on Column

5m

Mass 1 Column – 10 kg/m

11,000N

500 N

500 N

500 N

500 N

500 N

500 N

Force on each column = + 11,000 N 3000 N

= 14,000 N

Try it Try it youself!youself! How much

weight does each lower support hold?

Mass 1 pole = x

Weight 1 pole = x

=

=

50 kg

5m 10kg/m 50kg

500 N

10

Force on columns = + 11,000 N 3000 N

= 14,000 N






Weight of Foundations = x

3. Load on . Load on FoundationsFoundations

14,000N

Force on Foundations = +

2000kg 10 =

34,000N

Mass Foundations – 2000kg

20,000N

14,000N 20,000N

=

Try it yourself:Try it yourself: How much weight do the bottom supports hold?






Force on Foundations = + 11,000 N 20,000 N

= 34,000N

Extreme WindExtreme Wind

normal air pressure

low air pressure

Tornado

Windflow over buildingsWindflow over buildings

high pressure

low pressure

low pressure

So how do I calculate wind load?So how do I calculate wind load?What things do you think affect wind load?

Zone Windspeed

(m/s)

55

50

47

44

39

33

Step 1 – Highest Windspeed Step 1 – Highest Windspeed

Pabal – 39 m/s

Wind speed is affected by local terrain

If you are on a hill, increase the wind speed by multiplying by 1.1

Safety Factor Safety Factor

Design wind speed = 1.1 x 39 m/s= 43 m/s

Pressure is the force per square metre on the building

Wind PressureWind Pressure

Pressure (N/m2) = 0.6 x windspeed2

= x x 430.6

1109 N/m2=

43

1m1m

Wind force is the specific force on a particular part of the buildingSafety Factor: account for internal pressure changes with a safety factor of 2

Wind ForceWind Force

Force (N) = Pressure (N/m2) x Area (m2) x Safety Factor

Wind ForceWind ForceForce (N) = Pressure (N/m2) x Area (m2) x Safety Factor

Force On Wall (N) = x x

Area Of Wall (m2) = x

=

=

9m 5m45 m2

21109 N/m2

9,9810 N

9m

5m

Wind Pressure = 1325 N/m2

Safety Factor = 2

45 m2

Wind Force (N)

Wind ForceWind ForceForce (N) = Pressure (N/m2) x Area (m2) x Safety Factor

Force On Roof (N) = x x

Area Of Roof (m2) = x

=

=

10m 4m40 m2

21109 N/m2

8,8720 N

10m

4mWind Pressure = 1325 N/m2

Safety Factor = 2

Wind Force (N)

40 m2

Activity – Own designs!Activity – Own designs!

Force (N) = Pressure (N/m2) x Area (m2) x Safety Factor

1 2Safety Factor of 1.2

Pressure (N/m2) = 0.6 x windspeed2

3

4

Structures load calculations shelters

Education

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