Chapter 5

Question 1

Ultimate limit state

Answer 1

The failure of the structure when subjected to extreme values of action

Question 2

Limit state of serviceability

Answer 2

The structure must remain functional for its intended use subject to routine loading

Question 2

Loads

Answer 2

• Permanent loads (fixed equipment, self-weight of structure, road surfacing)
• Variable actions (imposed loads, beam and roofs, wind actions)
• Accidental actions (explosion, impact from vehicles)

Question 2

Individual bars or pairs or bars one above the other (Pitch)

Answer 2

• Min. horizontal pitch - 75mm (sufficient space for insertion of poker vibrator), 100mm for pairs of bars
• Min. vertical pitch - 25mm or bar Ø, whichever greater
• Max. pitch distance - Tension bars: 165mm, Compression bars: 300mm

Question 3

Required minimum bar spacing is aimed primarily at

Answer 3

• Obtaining adequate compaction and bond
• Ensure that the space between top bars is sufficient for vibrators to be used

Question 4

Curtailment of bar for beam

Answer 4

• Hanger bars
• Top bars at internal support
• Bottom splice bars at internal support
• Bottom bars in span
• U-bars at end of beam