1. Reinforced Concrete VS Steel
(1) Materials
Reinforced Concrete
VS Steel

2. Materials Reinforced Concrete Advantage
good resistance to weather & chemical, and good sound and thermal insulation
the structure system is more rigid, thus, less severe problem associated with sway deflection, floor vibration, and local column buckling
higher fire resistance
minimal maintenance is required
materials required to make concrete are readily available in the local market, thus no pre-ordering is necessary
local contractors are firmly familiar with RC construction
can be cast into any versatile shape, thus, allow more flexible design
fairly tolerable on last minute changes from Client and Architect
waterproofing can be easily applied with different degree of waterproofing
can produce a good finished surface, thus, no painting is necessary

3. Materials Reinforced Concrete Disadvantage
general heavier and hence more expensive foundation resulted
special care must be taken to ensure esthetic appearance against cracks induced by creeping and shrinkage effects
intensive amount of falsework and shuttering are required
easily affected by weather condition, this will prolong construction time

4. Materials Steel Advantage fast construction, weather independent
flooring can be cast at the same time where formwork are provided by un-propped corrugated steel decking
lightweighted, thus, less expansive foundation can be designed (i.e. shallow foundation.)
assembly is simple, since all members can be pre-fabricated prior to delivery to site
structure tends to be shallower in structural depth, thus, more space will be provided for service routing
with high strength to weigh ratio, suitable for long span construction.

5. Materials Steel Disadvantage
Long pre-ordering and delivery time would be required since majority members are to be import from overseas
Early decision on member size & connection details are required so as to allow for ordering and shop drawing preparation.
Steel members require special treatment and protection on fire & corrosion.
Special surface treatments are needed:
Low cost – Sprayed System (Mineral fibre sprayed systems, Vermiculite/gypsum/cement system)
External System (Mineral fibre boards/batts, Vermiculite/gypsum boards, Plasterboard)
Preformed System
Intumescent Coatings
Water or Concrete filled structural hollow sections
Concrete casings

6. Materials Steel Disadvantage frequent maintenance is required
skilful labors are required for fabrication, erection, and welding
large area on site is required for storage of structural member prior to erection
sensitive to temperature change and vibration
steel members will deflect appreciably under total load, needs pre-cambering
fabrication needs heavy plant and crane

7. (2) Structural Systems Vertical Load Supporting System
Lateral Load Supporting System (x & y directions)

8. Structural Systems Cantilever without back span
Columns do not vertically align
Too long cantilevers
Cantilever from column without back span
Heavy loading on long span transfer beam
Long Slender Columns

9. Floor Supporting Systems
(3) Structural Forms
Floor Supporting Systems

10. Deflection depends on:
Structural Forms
(Floor Supporting System) L w
Shear α L
Moment α L2
Deflection α L4
Deflection depends on:
Span
Structural Depth
Loading
Restraints

11. Structural Forms
Different forms of Bracing
(Bracing)

13. Athletic Centre, Sydney, Australia

14. State Hockey Centre

16. Irregular Form

17. Federation Square

20. (4) Preliminary Member Sizing

21. Typical service zone requirements

22. Reinforced Concrete RC beams Typical s /d Typical span Continuous
15 – 20
10 – 15
Up to 10m
10 – 20m
Simply supported
12 – 15
8 – 12
Cantilever
5 – 7 7m

23. Steel Element Typical s /d Typical span
Floor beams (UB’s) (include floor slab
15 – 18
Up to 12m
Plate girder
10 – 12
Castellated UB’s *
14 – 17
12 – 20m
Lattice girders (RSA’s) +
12 – 15
Up to 35m
Lattice girders (Tubular)
Up to 100m
Roof trusses (pitch >20o)
14 – 15
Up to 17m
Space Frames
20 – 24
Up to 60m
* Avoid if high point loads; increase Ireq by 1.3
+ Precamber by L/250

24. Typical column size

25. Appendix: Preliminary design charts

26. Appendix: Preliminary design charts (cont’d)

27. Appendix: Preliminary design charts (cont’d)

28. Appendix: Preliminary design charts (cont’d)

29. Appendix: Preliminary design charts (cont’d)

30. Appendix: Preliminary design charts (cont’d)

31. Appendix: Preliminary design charts (cont’d)

32. (4) References
Fuller Moore, Understanding Structures, Boston, WCB/McGraw-Hill, 1999.
Institution of Structured Engineers, Manual for the design of reinforced concrete building structures, London, the Institution, 1985.
Institution of Structured Engineers, Manual for the design of steelwork building structures, London, the Institution, 1989.
Ove Arup & Partners, Structural scheme design guide, London, Arup Research & Development, 1998.