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Guide to Long-Span Concrete Floors

Quiz Questions

1. Which of the following should be considered in the preliminary design?
Lateral load-resisting systems.
Framing plans.
Preliminary member sizes, including floor thicknesses. These may be based on span-to depth ratios, the charts in this Guide or a preliminary structural design carried out to confirm proposed sizes.
Control of volume change deformations and restraint forces.
Connection concepts.
None of the above
All of the above
2. Which of the following should be considered to confirm if the project is economically viable?
Architectural appearance.
The standard of quality and the broad requirements for the structure.
How the structure will perform and how it is to be built.
Preliminary cost estimate.
All of the above
3. The thickness of the floor zone ________than the overall depth of the floor system. It includes the depth required for any floor finishes, set downs or set ups, falls, and the depth required to accommodate below floor building services.
is not grater
is greater
4. Figure 1 is:
Piping installation.
AC duct work.
Typical floor zone.
5. In modern buildings the floor zone may often include:
air conditioning ductwork and fan coil units
ventilation and exhaust ducts
sanitary floor traps and waste pipes
stormwater waste pipes, hot and cold water
fire water and sprinklers
smoke detectors
data and electrical cabling
lighting and many other specialist services
All of the above

Services need to move horizontally along and across the floor and vertically from floor to floor in a building without clashing. The architect, structural designer and the services designer __________ liaise closely to ensure that services such as ducts, cables and the penetrations for the services do not jeopardize the structural behavior of the floor system or the operation of the building.

should not
7. Designers should appreciate that deflection _________ as important as strength in the structural design of concrete floors, particularly in the design of shallow reinforced concrete floors systems. Special attention should be given to the proportioning of the floor system for deflection before the final design.
is just
is not
8. Cantilevers are often used for balconies and along the external edge of a building to balance the internal span and/or improve the shear capacity at edge and corner columns Figure 5. Regardless of the floor system chosen they always need careful consideration. Cantilevers are usually limited to a span of about _______ of the back span and should be supported by a stiff support such as a beam or column.
25 to 35%
40 to 60%
9. Traditionally, concrete floor systems are reinforced using bars, fabric or using high-strength strand which is stressed. The action of prestressing with a straight or a draped cable in concrete enables the applied loads to be balanced by the uplift force so that practically no deflection results. This is a significant benefit in long-span floors as it eliminates the need to camber formwork or to provide deeper reinforced concrete sections.
10. Figure 10 Shows:
A reinforced concrete floor.
Flat plate floor system.
Beam and slab system.
11. Which one of the following are advantages of beam and slab?
Traditional effective solution.
Long spans.
Both of the above
12. Which one of the followings are disadvantages of beam and slab?
Penetrations through beams for large ducts difficult to handle
Depth of floor
Greater floor-to-floor height.
All of the above
13. Which one of the followings would be considered as advantages of Band Beam and Slab?
Relatively simple formwork
Shallow beams to allow services to run under the floor
Minimum structural depth and reduced floor-to-floor height
Long spans
Good cost/time solution
Allows the use of flying forms.
All of the above
14. Which one of the following would be disadvantages of band beam and slab?
Long-term deflection may be controlling factor and post-tensioning may be required
May need service penetrations through beams which are difficult to handle.
Both of the above
15. In which of the following conditions would solid slabs be chosen?
The loading results in high shear or there are heavy point loads.
The environment is aggressive, for example in splash zones or where condensation may occur over water.
High cover or special concrete is required.
Projecting reinforcement requires the units to be wet-cast, for example when used as a soffit beam to support hollowcore.
All of the above.