8/10/2019 Multi-storey Framed Structures
1/23
8/10/2019 Multi-storey Framed Structures
2/23
8/10/2019 Multi-storey Framed Structures
3/23
What is Multi storey Building?
A multi-storey building is a building that hasmultiple floors above ground in the building.
Multi-storey buildings aim to increase thearea of the building without increasing thearea of the land the building is built on,
hence saving land and, in most cases, money(depending on material used and land pricesin the area).
8/10/2019 Multi-storey Framed Structures
4/23
Abu Dhabi InvestmentAuthority Tower
International Commerce Centre,
Hong Kong
8/10/2019 Multi-storey Framed Structures
5/23
NO. OF STOREYS
Multi-storey building consists of buildingsof more than 1-storey.
MATERIAL
Construction materials may differdepending on the number of storey of the
building. Timber can be used for building not more
than 3-storeys high.
8/10/2019 Multi-storey Framed Structures
6/23
Steel Reinforced Concrete
Timber
8/10/2019 Multi-storey Framed Structures
7/23
Availability of material / labour Cost
Speed of erection
Method of construction Transportation
Possibility of standardizing the sizes of thestructural members
Size and nature of site Modification
Fire resistance required
8/10/2019 Multi-storey Framed Structures
8/23
For buildings of more than 5-storeys high, steelis the most suitable material to be used.
Steel is: Light in weight - easy to transport; less load on
foundation
Inorganic - will not decay, bend, crack or peel off High strength & durabilitysafety structure; Quality control - prefabricatedin the factory under
effective quality control less manpower, fasterconstruction
Less maintenance;
Cost effective;
Not at risk to delays
8/10/2019 Multi-storey Framed Structures
9/23
Heavier; dead load; Non-recyclable;
High risk in crack & mould growth;
Higher total cost;
Duration of work long, risk to delay
Flexible design
8/10/2019 Multi-storey Framed Structures
10/23
Element Steel Concrete
Site
consideration
Made under factory conditionBS/MSFabricated off site
Strict supervision on site
Work carried on site
Cost andspeed oferection
Erection by skilled- labour,quickly and accuratelyEarly completion but may belimited due to the large
number of complicatedconnections
Combination of skilled andunskilledSite space required forstorage and mixing
Cheaper in cost but longer inconstruction
Designconsideration
Extension need to expose bythe removal of any fireresisting casing
Flexibility in design monolithic in nature and notconfine to standard sectionsbut limit to the cost offormwork
Fireresistance
Requires protective covervarying in nature andthickness / sprayed asbestos
Provide a substantial degreeof fire resistance varied bythe cover thickness
Type ofconstruction
Dry constructionClean site
Wet constructionMessy site
8/10/2019 Multi-storey Framed Structures
11/23
8/10/2019 Multi-storey Framed Structures
12/23
FLOOR SYSTEM
The principal structural elements of a typicalmulti-storey building comprise floors, beams
and columns. A wide variety of alternativeforms and arrangements can be used in multi-storey steel framed structures.
Floor slabs:Severaldifferenttypes of slabcan be used,in either
composite ornoncompositeform.
8/10/2019 Multi-storey Framed Structures
13/23
COMPOSITE FLOOR SYSTEM The system consist of simply supported universal
Beam acting compositely with a thin concrete slab(concrete topping) supported on metal deck
Metal decking, which spans between secondarysteel beams usually spaced at between 2.5 and 3mcentres.
Steel stud are welded through the decking onto the
flange of the beam below to form a connectionbetween steel beam and concrete slab
Concrete is then poured onto the decking, usuallyby pumping, to make up the composite system.
Metal decking acts both as permanent formwork for
the concrete, eliminating the need to provide props,and as tensile reinforcement for the slab.
Steel bars are included in the slab to preventcracking and to provide reinforcement in the eventof degradation of the decking in a fire.
8/10/2019 Multi-storey Framed Structures
14/23
8/10/2019 Multi-storey Framed Structures
15/23
8/10/2019 Multi-storey Framed Structures
16/23
Slimdek is a proprietary shallow floor system. It is acomposite system comprising of an asymmetric slim
floor beam contained within the depth of the slab.
8/10/2019 Multi-storey Framed Structures
17/23
There are many types of steel deckingavailable. Some of the advantages of thecomposite metal deck system are: act as permanent shuttering which can eliminate
the need for slab reinforcement and propping ofthe construction. The floor deck serves as a working platform
during construction and as formwork for asitecast concrete slab
reduce the overall depth of structure. Provides upto 2 hours fire resistance (500C collapse)without additional fire resistance and 4 hourswith added thickness or extra surface protection.
8/10/2019 Multi-storey Framed Structures
18/23
light, adaptable system that can be cut awkwardshapes and can easily be drilled or cut out foradditional service requirements. Reduce frameloading and foundation cost.
Simple, rapid construction
8/10/2019 Multi-storey Framed Structures
19/23
8/10/2019 Multi-storey Framed Structures
20/23
NON - COMPOSITE FLOORSYSTEM
For shorter spans, precastconcrete floor slabs can beused with steel beams. Theprecast units may besupported on the top flangeof universal beams or onthe bottom flange
8/10/2019 Multi-storey Framed Structures
21/23
Universal beams supporting pre-cast floorunits have advantages over other forms ofconstruction.
This system offers:
Fewer floor beams since pre-cast floorunits can span up to 6 to 8 m. without thedifficulty. No propping is required.
Shallow floor construction can be obtainedby supporting pre-cast floor units on shelf
angle. Fast construction because no time is
needed for curing and development ofconcrete strength.
8/10/2019 Multi-storey Framed Structures
22/23
Disadvantages: Composite action not readily achieved
without a structural floor screed.
Heavy floor unit are difficult to erect inmany location and require use of specialmachines.
Small opening can be cut in the field,narrow openings parallel to slab span arepreferred, engineering analysis is requiredfor wide opening
8/10/2019 Multi-storey Framed Structures
23/23
Apart from the method of construction, theappropriate choice of building materials isamongst the important factors in theconstruction of multi-storey buildings. The
material for structural frame can be madefrom steel, in-situ reinforced concrete andpre-cast concrete.
Compare the choice between steel structuresto pre-cast concrete frame based on theprincipal factors considered in their selection.