Multi storey structural steel structures

MultiMulti--storeystorey
structural Steel Structuresstructural Steel Structures
www.onlinecivil.tk
Present By
J Thomas Britto
Dept of Civil Engineering

BackgroundBackground
Steel has been used for constructing buildings in the westernSteel has been used for constructing buildings in the western
world for more than 150 years. With the introduction ofworld for more than 150 years. With the introduction of
standard sections by the end of 19standard sections by the end of 19thth
Century, steelCentury, steel
structures were getting much more popular as a choice ofstructures were getting much more popular as a choice of
construction for highconstruction for high--rise buildings.rise buildings.
The use of structural steel to construct started only in the 70The use of structural steel to construct started only in the 70’’ss
in HK, below is some of the projects being completed:in HK, below is some of the projects being completed:
1.1. Park Lane Hotel (Causeway Bay, 1972)Park Lane Hotel (Causeway Bay, 1972)
2.2. Grand Hyatt & Harbor View Hotel (HKCEC Phase I, 1990)Grand Hyatt & Harbor View Hotel (HKCEC Phase I, 1990)
3.3. Bank of China Tower (Central, 1991)Bank of China Tower (Central, 1991)
4.4. Time Square (Causeway Bay, 1992)Time Square (Causeway Bay, 1992)
5.5. Lee Garden Redevelopment (ManuLee Garden Redevelopment (Manu--life Tower, 1997)life Tower, 1997)
6.6. The Center (Central, 1999)The Center (Central, 1999)
7.7. Cheung Kong Center (Central, 2000)Cheung Kong Center (Central, 2000)
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Properties of steelProperties of steel -- Steel has the followingSteel has the following
properties, that makes it one of the most efficientproperties, that makes it one of the most efficient
materials for use in building construction.materials for use in building construction.
Favorable propertiesFavorable properties
-- Strong: has a high strength/weight ratioStrong: has a high strength/weight ratio
-- Versatility: adaptable and ductileVersatility: adaptable and ductile
-- Cheap and plentifulCheap and plentiful
-- Easy to cut, connect and fabricateEasy to cut, connect and fabricate
Some drawbacksSome drawbacks
-- Heavy and lengthy, not easy to handleHeavy and lengthy, not easy to handle
-- Loss strength under higher temperatureLoss strength under higher temperature
-- Easily get rust if not properly treatedEasily get rust if not properly treated
-- Deflect under loadsDeflect under loads
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The use of structural steel sectionsThe use of structural steel sections
The availability of steel sections in a varietyThe availability of steel sections in a variety
of dimensional ranges provides theof dimensional ranges provides the
designers with a wide variety of designdesigners with a wide variety of design
options.options.
These sections are manufactured inThese sections are manufactured in
convenient shapes, sizes and thickness.convenient shapes, sizes and thickness.
They can be readily fabricated,They can be readily fabricated,
combined and connected to formcombined and connected to form
unlimited possibility of designsunlimited possibility of designs

Standard structural steel sectionsStandard structural steel sections
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Typical jointing details for structural frameTypical jointing details for structural frame
ColumnColumn
connects to baseconnects to base
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Connecting HConnecting H--column to form continual columncolumn to form continual column
Using splice plate
Using welded joint
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Connecting
beam to
column
Connecting
beam to
beam
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Typical layout of structural frameTypical layout of structural frame
Simple cage frame cantilever frame
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Propped cantilever frame

Wind-braced structures

Core structure

Characteristic of various kinds of structuralCharacteristic of various kinds of structural
steel framed structuressteel framed structures
In general, the performance of steel frameIn general, the performance of steel frame
structure may be affected by the followingstructure may be affected by the following
factorsfactors
a)a) Length of spanLength of span
b)b) Composition/continuity of spanComposition/continuity of span
c)c) Methods of jointing the membersMethods of jointing the members
d)d) Movement and deflection allowedMovement and deflection allowed
When using inWhen using in lowhaslowhas very good and efficient.very good and efficient.
Favorable properties of steelFavorable properties of steel
-- Strong: has a high strength/weightStrong: has a high strength/weight ratioentifulratioentiful
-- Easy to cut, connect andEasy to cut, connect and fabricatefabricategetget rust if notrust if not
properly treatedproperly treated www.onlinecivil.tk

Principle factors affecting choice of framePrinciple factors affecting choice of frame
Structural Design considerationStructural Design consideration
nn Foundation considerationFoundation consideration
nn Standardization of members or designStandardization of members or design
nn Span and floor loadsSpan and floor loads
nn Fire resistance requirementFire resistance requirement
nn Maintenance considerationMaintenance consideration
nn Integration of architectural & structural elementsIntegration of architectural & structural elements

Features of structural steel constructionFeatures of structural steel construction
Structural characteristicsStructural characteristics
1.1. Steel has lower dead load (unless encased inSteel has lower dead load (unless encased in
concrete)concrete)
2.2. Steel frame can easily to have the layout changed toSteel frame can easily to have the layout changed to
suit new design than concrete, especially requiringsuit new design than concrete, especially requiring
alteration after completion of the building.alteration after completion of the building.
3.3. Easily accommodate building movements for steel isEasily accommodate building movements for steel is
a relatively flexible material and have greatera relatively flexible material and have greater
adaptability to take up strain and deformationadaptability to take up strain and deformation
4.4. However, it is weaker in fire resistance for steel willHowever, it is weaker in fire resistance for steel will
lose strength and deform serious at higherlose strength and deform serious at higher
temperature (at 600temperature (at 600oo
C or above). This can beC or above). This can be
improved by applying fire resistant plasterimproved by applying fire resistant plaster
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Structural characteristics (continue)Structural characteristics (continue)
5.5. Beams usually shallower in size than for concreteBeams usually shallower in size than for concrete
BeamsBeams
6.6. Sections in various convenient type and size thusSections in various convenient type and size thus
economical in design and useseconomical in design and uses –– refer to standardrefer to standard
steel sectionssteel sections
7.7. Produce larger deflection & deformation (Bend)Produce larger deflection & deformation (Bend)
under windunder wind –– this will causethis will cause uncomfortuncomfort to users ofto users of
buildingbuilding
8.8. Steel has higher thermal expansion valueSteel has higher thermal expansion value
9.9. Rusting or corrosion problemsRusting or corrosion problems –– very strict antivery strict anti--
corrosion treatment has to be appliedcorrosion treatment has to be applied

Features of structural steel construction (cont.)Features of structural steel construction (cont.)
Construction aspectsConstruction aspects
1.1. Quicker to erect and can be prepared offsiteQuicker to erect and can be prepared offsite –– inin
workshop/factory environment with goodworkshop/factory environment with good
production and quality controlproduction and quality control
2.2. Erection on site less affected by climaticErection on site less affected by climatic
conditionsconditions –– without placing of concretewithout placing of concrete
3.3. Longer and highly coordinated planningLonger and highly coordinated planning –– requirerequire
long time to make structural design, fabricationlong time to make structural design, fabrication
and deliveryand delivery
4.4. Higher requirement in the control of dimensionalHigher requirement in the control of dimensional
accuracy before and during construction (inaccuracy before and during construction (in
fabrication and in erectionfabrication and in erection

Features of structural steel construction (cont.)Features of structural steel construction (cont.)
5.5. Demand greater transportation orDemand greater transportation or cranagescranages
provisionprovision
6.6. Complicated quality assurance proceduresComplicated quality assurance procedures ––
especially in the control of welding connectionespecially in the control of welding connection
7.7. Difficult to make connection with rigid structuresDifficult to make connection with rigid structures ––
especially in composite structure in which RC coreespecially in composite structure in which RC core
structure is involvedstructure is involved
8.8. More complex when building become moreMore complex when building become more
gigantic and tallergigantic and taller –– due to the huge number ofdue to the huge number of
structural members, some may be of very heavystructural members, some may be of very heavy
section (e.g. those stiffening members)section (e.g. those stiffening members)
9.9. Induce more works at higher altitudeInduce more works at higher altitude www.onlinecivil.tk

StiffeningStiffening
members in themembers in the
form of outrigger,form of outrigger,
belt truss orbelt truss or
transfer truss istransfer truss is
very difficult tovery difficult to
install during theinstall during the
constructionconstruction
processprocess
Outrigger tying up the coreOutrigger tying up the core
wall and the outer framewall and the outer frame
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Detail of the outrigger andDetail of the outrigger and
transfer truss system usedtransfer truss system used
in Cheung Kong Centerin Cheung Kong Center

The actual process inThe actual process in
installing the transfer trussinstalling the transfer truss ––
a temporary support framea temporary support frame
erected for the purposeerected for the purpose
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The completion of theThe completion of the
belt/transfer truss andbelt/transfer truss and
outrigger at various stagesoutrigger at various stages

Construction aspectsConstruction aspects –– highlight of somehighlight of some
problemsproblems Delivery of structural steel
member by ship
Large member delivery to site
waiting to hoisting up for erection
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Hoisting of the structural steel
member to the upper floor
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Connecting steel members with RC
element – an anchor frame may be
required for making strong connection
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To connect floor to core wall – starter bars
are to be provided within the core structure
Constructing the composite floor
in steel/RC composite structure
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Very large component often in
complicated shape www.onlinecivil.tk

Huge amount of structural members
make erection very complicated
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The existence of very complicated
jointing in steel structure

–– highlight of some problemshighlight of some problems
Required to perform works
at very high altitude www.onlinecivil.tk

Workers work at high altitude
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Connecting large and complicate shaped
components can be very difficult
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Examples of location where unmatched dimension causing problem
Concrete has to be trimmed
to allow steel to pass through www.onlinecivil.tk

Examples of location where unmatched dimension causing problem
Roof truss and
the decking not
on the same level
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Future development of using structural steel or
composite structures in Hong Kong
Instead of building very large and complex building using
composite manner, which resulted to very high cost in
construction, the following ways may be adopted in order
to achieve more cost effective application of technology in
future.
1. Use more simple and straight forward design like regular steel
frame structure in grid layout
2. Use more standardized components such as universal sections,
lattice trusses or prefabricated standard sections in the design
3. Apply more to other types of building structure/construction as
in many developed country like Japan, USA, or even Korea and
Taiwan
4. Forming hybrid structure with other prefabricated elements
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The use of standard structural
steel members in construction
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Convenient products in market allowing
the use of very cheap and effective
ready-install structural steel members to
form various building systems

A hybrid structure in Melbourne, Australia with the mixed use of
Precast concrete, cast-in-situ concrete and steel composite
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Detail of the hybrid elements
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End of presentationEnd of presentation

Multi storey structural steel structures

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