Forces And Structures

Question 1

Frame structure

Answer 1

Structure that has a combination of beams, columns and slabs to resist loads. Has a ‘skeleton’

Question 2

Shell structure

Answer 2

Usually thin, curved plate structures shaped to resist loads. Eg car, egg

Question 3

Difference between static and dynamic force

Answer 3

Static: A force that acts on one place. Does not move. Eg parked car

Dynamic: A moving force. Eg. A moving car

Question 4

List 5 forces and describe

Answer 4

Tension- pulling 
Torsion-twisting
Bending-both compression and tension
Shear-material moves in opposite directions, like scissors
Compression-pushing

Question 5

Triangulation

Answer 5

The use of triangles to give stability to structures. Eg. A crane

Question 6

Purpose of strut, tie, gusset plates, triangulation

Answer 6

Strut-resists compression
Tie-resists tension
Gusset plates-supports corners
Triangulation- resists both tension and compression

Question 7

What is the neutral axis

Answer 7

Centre line down a structure

Question 8

Unit of force

Answer 8

Newtons

Question 9

What adds rigidity to structures?

Answer 9

Strut, tie, gusset plate, triangulation.

Also the material being used and the actual shape or form

Question 10

Describe i section beam

Answer 10

Most common form of beam.

Also called ‘rolled steel joice’

Question 11

Advantages of tubular sections

Answer 11

More cost effective
Light weight

Means hollow, can be circular or square

Question 12

Def of torque and units

Answer 12

Torque is a turning force.
Measured in Newton/meters (N/m)
Also described as a moment.

Question 13

How to calculate torque

Answer 13

Force x Distance

The greater the distance from the fulcrum the greater the torque generated.

Question 14

The principle of moments

Answer 14

Clockwise moments=Anti-clockwise moments.

F1 x D1= F2 x D2

Question 15

Note!

Answer 15

Weight is equal to mass by gravity! (9.81)

Question 16

Factor of safety

Answer 16

Ratio of its actual loading capability over its required loading capability expressed as a percentage.
OR
The ultimate stress over the normal working stress.

Question 17

Beam calculations

Answer 17

Assume one of the supports is a pivot then calculate using the principle of moments. To calculate second support take the force of the other support away from the overall downward force.