1. BE2S71 Construction Technology 2
Framed Buildings
Ref; Civil Engineering Construction Design and Management; D R Warren
CORUS
British Cement Association

2. Superstructures
Defined as: -“construction of buildings above ground level”
Before the turn of the 20th century buildings were restricted in height due to the required thickness of load bearing brickwork
The development of the lift in 1880 has been seen as the catalyst to high rise frame construction i.e. not limited by the means of stairs to access higher storeys.
Meant building could extend upwards.; lighter in weight and have greater window area

3. Conventional Superstructure
Is now a framed structure using: -
Long Span / Medium Rise Structures
Beams / Columns to support roof; floor and cladding
Competition between steel and concrete and popularity depends upon variations in price

4. Floor Space
Client; Architect usually want as much uninterrupted floor price as possible
Because buildings are priced on floor area and must be flexible enough to accommodate varying internal partition arrangements as the use may change many times throughout their design life
But they do have the disadvantage of internal columns which reduce and dictate layout

5. Composite Construction
One step to overcoming these disadvantages is by using composite construction of steel and concrete that will assist in achieving long spans

6. Functional Requirements
The main functional requirements are: -
Strength
Stability
Durability
Fire safety

7. Long Span
Low Rise Buildings
One or Two Storey
15m – 20m in height

8. Construction Portal Frames Trusses Latticed Portals Space Frames
Shell Roofs

9. Portal Frame Connections
Provides a clear open space
Spans 12 – 45m

10. Stability
The designer should consider the stability of the structure in all directions
Each joint in the framed structure must be systematically considered i.e. x, y and z directions north; south and up

11. Trusses
Often used instead of portal construction as they can span large distances
Trusses can carry a huge variety of loading patterns ideal for industrial applications
Difficult to prefabricate and transport and can cost up to 20 – 30% more than a portal frame

12. Medium Rise Structures
Defined as up to four storeys medium rise structures are the most common form of construction in the UK
Such structures are usually framed structures and can be constructed of concrete and or steel

13. Concrete Flexible in form; Robust structure
Capable of carrying a wide variety of loadings ideal for a change of use
Noise insulation from both internal and external sources
Provides fire insulation
Slower to construct
Either pre-cast or cast in-situ
Expensive?

15. High profile failures Alkaline Aggregate Reaction (AAR);
Lafarge has been selling RMC from Sept 2002 – Dec 2004 across the South East of England with excessive levels of Alkaline which has been linked to the development of concrete cancer
Poor workmanship may lead to carbonisation

17. Concrete Three materials used in production of concrete Cement
Aggregate
Sand and Water

18. Cement Portland Ordinary Rapid Hardening Sulphate resisting White
Low heat
Blast furnace
Water repellent

19. Aggregates Natural Artificial Fine and Coarse Grading
Particle size and shape
Water

20. Reinforcement

21. Reinforcement

22. Pre-cast Concrete Is fast to erect and cheaper than in situ
Manufactured off site in factory controlled conditions
High Quality
But usually provides thick floor slabs due to down stand beams to provide support
But can be inflexible if design on construction errors occur

23. In-situ Concrete Requires intensive on site labour operations
Weather can dictate on site operations
Space requirements = storage; cleaning lifting off loading areas
Formwork – Falsework
Reinforcement
Curing of concrete
Slow follow on for trades

24. Formwork

27. Steel Frame “Meccano Concept”
So called because it requires small number of repetitive parts and is assembled on site in what is basically a “Kit” construction.
Pre-fabrication is rigorously controlled and accuracy and quality is guaranteed (nearly always) highly skilled factory workforce with quality control checks at all stages of production.

28. Skeletal Steel Framed Buildings

29. Steel Framed
Essential that factory and site are in possession of correct and updated drawings and specifications, setting out of stanchion base must be accurate as components are accurately produced to specification
Most of the work is undertaken during production.
Specialist teams assemble frame on site.
Uses modular and dimensional co-ordination for success.

30. Structural Steel Frames
Skeleton frames support and transmit all loadings
Economics generally dictate member arrangement. Columns are arranged on a rectangular grid layout.
Typically they may be 3 ‑ 4 metres apart and parallel to the span of the floors. Floor beams may be up to 7.5 metres. The floors are designed to span one way.
Should greater clear spans be necessary secondary beams may be introduced.
Greater span is attained by an increase in structural depth of the floor support structure hence increasing floor to floor height and hence construction costs.

31. Steel Frames
Controlled factory workshop environment all year good conditions enables high productivity
Ideal material for fast prefabricated construction
Utilises stock of Pre-Made sections cut to length, fixing cleats welded and bolt holes drilled for site assembly of finished components
Most work pre- fabricated off site in workshop
Little or no on-site storing of component
Prefabricated can be installed same time as foundations
Little on site work and easily carried out
Light members with low cross sectional areas require only mobile crane for installation :-

32. Steel Frames
Factory made high accuracy close tolerance. Pre-fabricated components enables quick and relative ease of on site installation
Swift assembly by bolting of few large pre-fabricated parts
Allows quick follow on of trades
Loaded on back of lorry by use of mobile crane for transport. Reduces hire period of mobile crane due to ease of loading.
Enables use of large pre-fabricated cladding and partition panels which further supports the “Meccano” concept
Well suited to Multi Storey construction on confined sites. Particularly when supported by programmed sequence of deliveries and direct incorporation of parts into building
There are drawbacks, needs protection from fire and corrosion

33. Hot Rolled Structural Steel Sections

34. Connections

35. Fire Protection of Steel Frames
Why is it important to protect steel against fire?
Loses its bearing capacity
At what temperature does steel lose its strength? 5500c
When does fire become a problem?
After the frame is erected
List two types of fire protection
Sprayed; Board Casings; Blocks; Concrete; Paint
How does the insulating barrier work?
Slows down the transfer of heat
How does the size of the section of steel affect its capacity to resist fire
Larger sections absorb more heat than smaller sections before reaching the critical temperature

36. Corrosion Protection of Structural Steel
To assist in the prevention of corrosion to steel what should be kept away from the surface: -
Oxygen
Water
Alternatively what can be used: -
Sacrificial metal such as Zinc or aluminium to discourage corrosion by an electrochemical reaction[
Name two methods of excluding moisture from the surface of steel
Put steel inside building where it will not get wet
Cover steel with a protective coating

37. Fire Protection of Steel

38. Corrosion Protection of Structural Steel
Protective coatings differ in their effectiveness in the following ways: -
Exclude water from the surface of the steel
Adhering to the surface
Resisting attack from Chemicals
Resisting degradation by exposure to sunlight
What are the two important factors that should be considered if maximum life is to be achieved along with minimum life cycle costs: -
Surface preparation
Design to avoid water collection
What dictates the choice of corrosion system?
Environment
Location

39. Composite Steel profiled decking

40. Composite Steel profiled decking

41. Composite Steel profiled decking