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Module Title : Temporary Works • 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.
Module Title : Temporary Works • (according to theGeneral 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.
Reading/Reference List • 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.
Reading/Reference List • 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.
Reading/Reference List • 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, (2005), Labour Department, HKSAR Government.
Reading/Reference List • 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.
Common Temporary Works in construction sites • Hoading & Fencing, Site offices, storage facilities • Excavation supports • Access Scaffolds • Working Platforms
Common Temporary Works in construction sites • Falsework • Shoring • Temporary Access Bridges, Ramp • Temporary Structures for Construction Plants • River Diversion Structures
Temporary Works and the Conditions of Contract • General Conditions of Contract for Civil Engineering Works, Hong Kong Government 1993 Edition • Clause 10 – Extent of Contract ( General Obligations )
Temporary Works and the Conditions of Contract • 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
Temporary Works & the Common Law • 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;
Temporary Works & the Common Law • (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;
Temporary Works & the Common Law • (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.
Temporary Works & Contract Pricing • Requirements of temporary works: labor, plants, materials, construction methods(including safety provisions) and the associated cost need to be established at the tender stage.
Temporary Works & Contract Pricing • 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
DESIGN OF TEMPORARY WORKS • 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.
DESIGN OF TEMPORARY WORKS • 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.
DESIGN OF TEMPORARY WORKS • III. documents provided by manufacturers marketing proprietary equipment tested to comply with the relevant local legislation/industrial standards.
DESIGN OF TEMPORARY WORKS • Why Standard Solutions ? • 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.
DESIGN OF TEMPORARY WORKS • Designed Solutions • Designed solutions become necessary for situations where the standard solutions are in appropriate. Competent persons should be employed in such particular site situations.
SCAFFOLDING • 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
SCAFFOLDING • Codes of Practice: • 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
Standards Lift Bay Ledger/Lacing Diagonal Brace Ledger Brace Plan Brace Transom Terminology in Scaffolding Layout
Terminology in Scaffolding Layout • Putlog • ..\Teaching_Notes\TEMP_WK\multimedia\Scaffold-PutlogEnd.jpg • Coupler • Guardrail • Decking/Boarding • Toeboard • Sole Plate/Board
U-head/Fork head ..\Teaching_Notes\TEMP_WK\multimedia\Soffit Form U-head.jpg Screw (U-head/Base)Jack Prop (telescopic) Tie rod Terminology in Scaffolding Layout
Terminology in Scaffolding Layout • Heavy Duty Shores/Towers • ..\Teaching_Notes\TEMP_WK\multimedia\Scaffold-Frame002.jpg • ..\Teaching_Notes\TEMP_WK\multimedia\Scaffold-Frame003.jpg
Standard 90 deg coupler Fixed coupler Swivel coupler Safety/Check coupler Putlog head Reveal pin Couplers & Fittings ..\Teaching_Notes\TEMP_WK\multimedia\Scaffold-Coupler.jpg
Types / Configurations of Scaffolds • 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.
Types / Configurations of Scaffolds • 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.
Types / Configurations of Scaffolds • 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)
Types / Configurations of Scaffolds • 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)
Types / Configurations of Scaffolds • 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.
Comparison between Tube & Fittings Scaffold and Proprietary Scaffold • Tube and Fitting Scaffold • Advantage • more flexible to awkward situations and dimensions which do not fit the modules of proprietary methods.
Comparison between Tube & Fittings Scaffold and Proprietary Scaffold • 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.
Comparison between Tube & Fittings Scaffold and Proprietary Scaffold • 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.
Comparison between Tube & Fittings Scaffold and Proprietary Scaffold • Proprietary Scaffold • Disadvantage: • the capital cost is grater than with tube and fittings.
Division between standard and designed solutions • 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.
Checklist for scaffolding requirements • 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
Checklist for scaffolding requirements • 4. Rubbish chutes • 5. Loading towers • 6. Internal wall and partition scaffold • 7. Birdcage access scaffold • 8. Mobile access towers • ..\Teaching_Notes\TEMP_WK\multimedia\Scaffold-MobileTower.jpg
Checklist for scaffolding requirements • 9. Truss-out Access scaffold • ..\Teaching_Notes\TEMP_WK\multimedia\Scaffold-TrussOut.jpg • 10.Handrails and guardrails • 11. Lift shafts • 12. Protective fans • 13. Other specialist requirements • 14. Protection requirements
Provisions in Scaffolding Contracts • 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.
Provisions in Scaffolding Contracts • 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.
Provisions in Scaffolding Contracts • 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.
Site Safety Regulationsfor Scaffolding Works • The responsibilities of a contractor in working with scaffolds under the Construction Sites (Safety) Regulations of Hong Kong are :
Site Safety Regulationsfor Scaffolding Works • (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, • (ii) ensure every place on the site shall be made and kept safe for any person working there • (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.
Site Safety Regulationsfor Scaffolding Works • (iv) ensure every scaffold is of good construction, made of strong and sound materials and free from patent defect and properly maintained. • (v) ensure every scaffold is kept so fixed, secured or placed in position. • (vi) no part of structure or building is used in support for a scaffold unless it is strong and stable.
Site Safety Regulationsfor Scaffolding Works • (vii) the scaffolds to be inspected by a competent person within the immediately preceding month, • (viii) inspection reports to be made in approved forms by the person who is responsible for inspection which contain the prescribed particulars and delivered to the contractor concerned.
Bamboo Scaffolds - Advantages Flexibility • 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. • 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.