Transcript Introduction to Temporary Works

Module Title : Temporary
Works
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Module Title : Temporary Works
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Module Title : Temporary
Works
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Definition
(according to BSI)
Any temporary construction necessary to
assist the execution of the permanent works
and which will be removed (sometimes not)
from the site on completion.
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Module Title : Temporary Works
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(according to the General Conditions of
Contract for Civil Engineering Works,
Hong Kong Government 1993 Edition)
All temporary work of every kind required
for the construction, completion and
maintenance of the Works.
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Reading/Reference List
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The Concrete Society and The Institution of
Structural Engineers, (1995), Formwork : A Guide
to Good practice, 2nd Edition.
2. Clear, C. A., & Harrison, T. A., (1985),
Concrete Pressure on Formwork, CIRIA Report
108.
3. Murray Grant (1982), Scaffold Falsework
Design, A Viewpoint Publication.
4. Construction Sites (Safety) Regulations, CAP
59, Law of Hong Kong, HKSAR Government.
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Reading/Reference List
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5. Illingworth, J. R., (1993), Construction
Methods and Planning, Chapman & Hall.
6. Doran, D., (2004), Site Engineers Manual,
Whittles Publishing.
7. Guidelines on the Design and Construction of
Bamboo Scaffolds, Buildings Department, HKSAR
Government.
8. Safety of Scaffolding Works in Construction Site
During Typhoon Seasons, (2010), Buildings
Department, HKSAR Government.
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Reading/Reference List
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9. Safety Guidelines for Demolition of Building
Structures, (2004), Occupational Safety & Health
Council
10. Code of Practice for Bamboo Scaffolding Safety,
(2009), Labour Department, HKSAR
Government.
11. Code of Practice for Safe Use & Operation of
Suspended Working Platform, (1999), Labour
Department, HKSAR Government.
12. Code of Practice for Metal Scaffolding Safety,
(2001), Labour Department, HKSAR
Government.
13. Code of Practice for Safe Use of Excavation, 7
(2005), Labour Department, HKSAR
Reading/Reference List
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14. Code of Practice on Design & Construction of
Tower Working Platforms, (2000), Electrical and
Mechanical Services Department, HKSAR
Government.
15. Code of Practice on Working Near Electricity
Supply Lines, (2005), Electrical and Mechanical
Services Department, HKSAR Government.
16. Code of Practice on Avoiding Danger from Gas
Pipes, (1997), Electrical and Mechanical Services
Department, HKSAR Government.
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Common Temporary Works in
construction sites
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Hoading & Fencing, Site offices, storage
facilities
Excavation supports
Access Scaffolds
Working Platforms
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Common Temporary Works in
construction sites
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Falsework
Shoring
Temporary Access Bridges, Ramp
Temporary Structures for Construction Plants
River Diversion Structures
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Temporary Works and the
Conditions of Contract
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General Conditions of Contract for Civil
Engineering Works, Hong Kong
Government 1993 Edition
Clause 10 – Extent of Contract ( General
Obligations )
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Temporary Works and the Conditions
of Contract
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The Contractor shall, subject to the provisions of
the Contract, execute the Works and provide all
labor, materials, Construction Plant, Temporary
Works, transport to and from the Site or in and
about the Works and everything whether of a
temporary or permanent nature required in and
for such execution so far as necessary for
providing the same is specified in or reasonably
to be inferred from the Contract
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Temporary Works & the Common
Law
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It shall be the duty of any person who
designs, manufactures, imports or
supplies any article for use at work,
(a)
to ensure, so far as is reasonably
practicable, that the article is so designed
and constructed as to be safe and
without risks to health when properly
used;
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Temporary Works & the Common Law
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(b) to carry out or arrange for the carrying
out of such testing and examination as
may be necessary for the performance of
the duty imposed upon him by the above
paragraph;
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Temporary Works & the Common
Law
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(c) to take such steps as are necessary to
secure that there will be available in
connection with the use of the article at work
necessary and adequate information about
the use for which it is designed and has been
tested, and about any conditions necessary to
ensure that when put to that use, it will be safe
and without risks to health.
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Temporary Works & Contract Pricing
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Requirements of temporary works: labor,
plants, materials, construction
methods(including safety provisions) and
the associated cost need to be established
at the tender stage.
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Temporary Works & Contract Pricing
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Otherwise the tender sum may not allow
sufficient budget for the subsequent site
activities in the construction phase, hence
decreasing the Contractor's profit margin
or to the worst incurring a significant loss
at the end of the Contract
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DESIGN OF TEMPORARY WORKS
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Standard Solutions
Solutions to temporary works problem by
reference to tables/charts previously
prepared for the likely variety of loadings
that could be met in situations amenable
to their use.
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DESIGN OF TEMPORARY
WORKS
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Relevant information could be available from :
I. in-house tabulations showing loads and
spacing of materials used on a standardized
basis;
II. authoritative guidance documents resulting
from research and testing e.g. CIRIA Reports,
B.S.
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DESIGN OF TEMPORARY WORKS
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III. documents provided by
manufacturers marketing proprietary
equipment tested to comply with the
relevant local legislation/industrial
standards.
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DESIGN OF TEMPORARY
WORKS
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Why Standard Solutions ?
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Requirements in relation to temporary works can
be assessed with good accuracy.
The pricing of various bill items will be more
accurate.
Standard solution tables provide site management
with the means of checking the work of
subcontractors involved in carrying out the
temporary works on site.
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DESIGN OF TEMPORARY
WORKS
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Designed Solutions
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Designed solutions become necessary for
situations where the standard solutions are in
appropriate. Competent persons should be
employed in such particular site situations.
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SCAFFOLDING
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Definition:
a crucial item to ensure that workers have a safe
place of work and a safe means of access to it.
Related legislation:
Strength and Stability; Platform widths for
various purposes; Provision of hand rails, toe
boards, prevention of materials falling off
scaffolds
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SCAFFOLDING
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Codes of Practice:
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BS 5973:1990 Code of Practice of
scaffolding (design code)
BS 1139:1981 Part 3 Specification for
prefabricated access and worker towers
No codes of practice for proprietary systems
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Terminology in Scaffolding Layout
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Standards
Lift
Bay
Ledger/Lacing
Diagonal Brace
Ledger Brace
Plan Brace
Transom
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Terminology in Scaffolding Layout
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Putlog
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Coupler
Guardrail
Decking/Boarding
Toeboard
Sole Plate/Board
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Terminology in Scaffolding Layout
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U-head/Fork head
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Screw (U-head/Base)Jack
Prop (telescopic)
Tie rod
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Terminology in Scaffolding Layout
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Heavy Duty Shores/Towers
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Couplers & Fittings
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Standard 90 deg
coupler
Fixed coupler
Swivel coupler
Safety/Check
coupler
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Putlog head
Reveal pin
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Types / Configurations of Scaffolds
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A. Tube and Fitting Scaffolds
Putlog Scaffolds :
scaffolds are those which have one line of
standards to support the outside of the scaffold
deck, while the inside edge is supported from the
wall being built. The 'putlog' is a transom
member with a flattened end to rest on masonry
walling. The whole scaffold erection is slightly
lean inwards to increase stability.
Limitation - for use on load bearing walls only.30
Types / Configurations of Scaffolds
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Independent Tied Scaffolds :
scaffolds are those have two rows of standards
supporting the working deck. The transom
members are tied between the two layers of
standards and act independent of what is being
built. For improving the overall scaffold
stability, the structure is tied at some points to
the new building.
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Types / Configurations of Scaffolds
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Special Scaffolds for specialised work
Free-standing scaffolds - movable and stable Vs
overturning without any attachment to any other
structure but occasional guy or raking strut
support. (Covered by BS 1139 : Part 3. 1983)
Slung Scaffold - those hanging from a structure
overhead but incapable of being moved sideways
or raised or lowered. (Covered by 5973:1990)
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Types / Configurations of Scaffolds
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Suspended Scaffolds - working
platforms suspended on wire ropes from a
suitable structure above, such that they
can be raised or lowered, but not moved
sideways. (Covered by 5974:1982)
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Types / Configurations of Scaffolds
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B. Proprietary Scaffolding Systems
The specialised systems are designed to
avoid the use of loose fittings and are modular
in concept. Their load carrying capacity and
structural stability work on a deem-to-satisfy
basis after extensive testing to validate the
performance figures by the respective
manufacturers.
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Comparison between Tube & Fittings
Scaffold and Proprietary Scaffold
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Tube and Fitting Scaffold
Advantage
more flexible to awkward situations and
dimensions which do not fit the modules of
proprietary methods.
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Comparison between Tube & Fittings
Scaffold and Proprietary Scaffold
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Proprietary Scaffold
Advantages:
Connection methods provide a rigid
connection to standards than conventional tube
and fittings
The members are of fixed modules and hence
the scaffold set out itself. If dimensions are
wrong, the pieces will not fit together.
It is easier and quicker to train scaffolders.
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Comparison between Tube & Fittings
Scaffold and Proprietary Scaffold
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Proprietary Scaffold
Advantages (Cont’d):
Few loose fittings are needed.
Quicker erection due to no coupling to be
set out or done up required in the tube
methods.
Losses are minimized because of the size
of the standard components.
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Comparison between Tube & Fittings
Scaffold and Proprietary Scaffold
Proprietary Scaffold
 Disadvantage:
 the capital cost is grater than with
tube and fittings.
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Division between standard and
designed solutions
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BS 5973 recommends that the design of Tube &
Fitting Scaffolds can adopt standard solutions (i.e.
without design calculation) up to 50 metres high
provided that they do not carry loads nor greater bay
lengths than those specified in the document, nor
subjected to loading of materials by mechanical
means.
The Proprietary Scaffold Systems all come into the
standard solutions. Any modified approach need to be
supported by designed solutions.
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Checklist for scaffolding
requirements
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Preparations for scaffolding specifications will
be assisted by having available a checklist
similar to one shown below of all possible
types of scaffolding that may be needed for
both internal and external construction
activities.
1. External elevations
2. Scaffold to roof level structures
3. Hoist towers
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Checklist for scaffolding
requirements
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4. Rubbish chutes
5. Loading towers
6. Internal wall and partition scaffold
7. Birdcage access scaffold
8. Mobile access towers
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Checklist for scaffolding
requirements
9. Truss-out Access scaffold
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10.Handrails and guardrails
11. Lift shafts
12. Protective fans
13. Other specialist requirements
14. Protection requirements
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Provisions in Scaffolding Contracts
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Responsibilities
1. The scaffold owner shall declare the loads that are
brought down by each standard. The hirer will be
responsible for adequate foundations and this
information on loading of standards is necessary for
him to provide the necessary support.
2. The hirer is responsible for the provision of
sufficient anchorage points for a positive tie into the
structure, in accordance with BS 5973 or as may be
agreed between the parties.
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Provisions in Scaffolding Contracts
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3. Those erecting the scaffold will ensure that the
scaffolding is soundly and adequately constructed and
complies with appropriate Regulations (esp. in
respect of safety) on handing over.
4. The legal requirements calling for regular
inspections of the scaffold thereafter rest with site
management.
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Provisions in Scaffolding Contracts
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Pricing
1. Provision of scaffolding as described by the
main or specialist contractor who is
responsible for its provision;
2. The extra over rate for the hire of the
scaffold if the contract period is overrun, as a
rate per week;
3. Hourly labor rates for alterations to the
scaffold after the initial erection.
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Site Safety Regulations
for Scaffolding Works
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The responsibilities of a contractor in working
with scaffolds under the Construction Sites
(Safety) Regulations of Hong Kong are :
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Site Safety Regulations
for Scaffolding Works
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(I) ensure practicable, suitable and sufficient safe
access to and egress from every place on site at which
any person at any time works, and maintain it
properly,
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(ii) ensure every place on the site shall be made and
kept safe for any person working there
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(iii) ensure that no scaffold is erected on the site or
substantially added/altered/dismantled except under
the immediate supervision of a competent person and
by competent workmen of adequate and appropriate
working experience.
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Site Safety Regulations
for Scaffolding Works
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(iv) ensure every scaffold is of good construction,
made of strong and sound materials and free from
patent defect and properly maintained.
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(v) ensure every scaffold is kept so fixed, secured or
placed in position.
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(vi) no part of structure or building is used in support
for a scaffold unless it is strong and stable.
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Site Safety Regulations
for Scaffolding Works
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(vii) the scaffolds to be inspected by a
competent person within the immediately
preceding month,
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(viii) inspection reports to be made
approved forms by the person who
responsible for inspection which contain
prescribed particulars and delivered to
contractor concerned.
in
is
the
the
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Bamboo Scaffolds - Advantages
Flexibility
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Bamboo could be cut and lapped through fastening thus
tailor-assembled easily to suit the profile and contour for
most construction structures even of very complicated
geometry and shape.
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Bamboo scaffolds could also be erected at any elevation
of a multi-storey building, for instance truss-out scaffold
structures, which is particularly advantageous in Hong
Kong where tall buildings are crowded with limited space
for access in general.
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Bamboo Scaffolds - Advantages
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Bamboo when combining with steel brackets
as the primary structural supports could be a
very safe solution for most scaffolding work.
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Bamboo Scaffolds - Advantages
Cost effectiveness
· Abundant supply of bamboo is available from the
Southern China areas, thus reducing the cost of
transportation for scaffolding work in Hong Kong.
· Fast growth in bamboo plantation could make it as a
cheap and environmental friendly temporary works
materials
 The cost is usually a few percent of that of steel
scaffolding tubes.
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Bamboo Scaffolds - Advantages
Speediness
· Bamboo is very light-weighted which can be
handled by workers and it requires no
machinery and sophisticated hand tools.
 This feature is leading bamboo scaffolds could
be erected and dismantled much faster than
other types of other types of scaffolding.
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Bamboo Scaffolds
- Common Causes of Failure &
Limitations
1.A safely erected bamboo scaffold could be put
into a dangerous access structure for
construction workers if other trade-workers
damage it through cutting bamboo elements to
suit their own operational needs e.g. plastering
work, plumbing.. etc.
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Bamboo Scaffolds
- Common Causes of Failure & Limitations
2. Immature bamboo was imported and used for
the scaffolding work, in particular when there
is a large over-consumption of bamboo in the
times when construction is a blooming
business.
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Bamboo Scaffolds
- Common Causes of Failure & Limitations
3. Inadequate of monitoring and
maintenance of bamboo scaffold erected
are not uncommon in local building sites.
Sometimes a bamboo scaffold is left
unattended for several months.
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Bamboo Scaffolds
- Common Causes of Failure & Limitations
4. Unskilled scaffolding workers are employed
to erect or dismantle bamboo scaffold.
Traditional skill and correct code of practice
are neither ignored nor carried out by
inexperienced workers which eventually
produce an unsafe temporary structure.
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Bamboo Scaffolds
- Common Causes of Failure & Limitations
5.Bamboo is a natural material bearing
biological defects which are difficult to be
characterised assessment in the current
engineering practices. Design and
construction of bamboo scaffolds depends on
skill and experience of the trade. Application
to very high-rise and heavy duty structural
works should be avoided.
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