ES196 - Engineering Structures

Question 1

Structure

Answer 1

• A permanent system or assembly of members
• Designed to transmit the loads safely
• To a means of support

Question 2

What to consider when designing structures

Answer 2

• safety
• aesthetics
• serviceability
• economic constraints
• environmental constraints

Question 3

Types of load

Answer 3

• gravity loads
• horizontal loads
• loads induced by extreme events

Question 4

Particle

Answer 4

• Small localised object
• Has physical properties but no dimension

Question 5

Rigid body

Answer 5

• Combination of a number of particles
• All particles remain at a fixed distance from one another before, during and after a force is applied to the object

Question 6

Force

Answer 6

• Vector
• Characterised by:
  
  • a point of application
  • magnitude
  • direction
• ‘Push’ or ‘Pull’ action

Question 7

Moment of a force

Answer 7

• The tendency of a rigid body to rotate
• Characterised by:
  
  • a force
  • a centre of rotation
  • a perpendicular distance between the centre of rotation and the application point of the force

Question 8

Equilibrium

Answer 8

• For a particle to be in equilibrium, the resultant force on the particle must be zero
• For a rigid body to be in equilibrium, the resultant force and resultant moment must both be zero

Question 9

Fluid

Answer 9

• Continuous substance
• Exerts only normal forces on its boundary surfaces
• When at rest
• Hydrostatic pressure for liquids, Aerostatic pressure for gases

Question 10

Roller joint

Answer 10

• Constrains: y
• Leaves free: x, z
• Imposes: Ry

Question 11

Pin joint

Answer 11

• Constrains: x, y
• Leaves free: z
• Imposes: Rx, Ry

Question 12

Fixed support

Answer 12

• Constrains: x, y, z
• Leaves free:
• Imposes: Rx, Ry, M

Question 13

Fixed with free translation

Answer 13

• Constrains: y, z
• Leaves free: x
• Imposes: Ry, M

Question 14

External forces on structures

Answer 14

• External loads
• Reactions at supports

Question 15

Internal force

Answer 15

• Force which holds an object together
• When external forces are applied
• Internal forces cause the structure to change in shape and size (deformation)

Question 16

Types of internal force

Answer 16

1. Axial (N) - force acting // to the centre axis of the object. Tension or compression
2. Shear Force (V) - force acting perpendicular to the centre axis of the object
3. Bending (M) - combination of tension and compression
4. Torsion (T) - twisting of an object about its centre axis