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1 978-1-74361-791-5 [Multi-Vol. Set] 978-1-74361-783-0 [PDF] 978-1-74361-784-7

1 978-1-74361-791-5 [Multi-Vol. Set] 978-1-74361-783-0 [PDF] 978-1-74361-784-7 [DOCX] Safe Work Australia Contact Information Phone 1300 551 832 | Email info@swa.gov.au | Web www.swa.gov.au This Guide provides information on designing, erecting, using and dismantling formwork. It is part of a series of guides for formwork and falsework that includes the: General guide for formwork and falsework Guide to slip, jump and travelling formwork systems Guide to falsework, and Information Sheet: Formwork and falsework. Formwork Formwork means the surface of the form and framing used to contain and shape wet concrete until it is self-supporting. Formwork includes the forms on or within which the concrete is poured and the frames and bracing which provide stability. Although commonly referred to as part of the formwork assembly, the joists, bearers, bracing, foundations and footings are technically referred to as falsework. Further information is in the Guide to falsework. Formwork construction may involve high risk activities like operating powered mobile plant like cranes, working at height and excavating foundations. Safe work method statements (SWMS) If the work involves high risk construction work, a SWMS must be developed in consultation with workers and their representatives who are carrying out the high risk construction work as defined under the Work Health and Safety (WHS) Regulations. Further information on high risk construction work, SWMS and a SWMS template is in the Code of Practice: Construction work. Design The design of the final concrete structure can have a major effect on the ease of formwork construction and the health and safety of people during construction. Generally the more basic and simple the final concrete structure, the safer it is to construct, erect and dismantle the formwork. An experienced formwork designer should be consulted during the design of in-situ concrete structures to enable the health and safety risks during formwork construction and dismantling to be considered in the design. The formwork designer must be competent in formwork design including documenting temporary work platforms and special equipment needed for safe formwork construction on-site. A designer may use a technical standard or a combination of standards and engineering principles relevant to the design requirements as long as the outcome is a design that meets regulatory requirements. Formwork should be: rigid, watertight, braced and tied together to maintain position and shape during construction , and able to be removed easily and safely without damaging the formed concrete, or have components that remain as part of the finished structure so the rest can be removed without damaging the structure. ! ! GUIDE TO FORMWORK 2 JULY 2014 GUIDE TO FORMWORK Formwork drawings should include details of: formwork and formwork joints sealing procedures ties size and spacing of framing details of proprietary fittings or systems proposed to be used, and bond breakers, if used. The formwork designer should determine the vertical pour rates for walls, columns and other vertical concrete elements before completing the formwork design. Details of the construction method and erection sequence should be included on the formwork drawings where appropriate. Where special methods like external vibration are involved the formwork design should allow for any resulting additional structural loads. Where formwork is to be re-used, the formwork design should ensure form strength is retained after allowing for the deterioration of materials through use, handling and storage. All formwork drawings should be certified as complying with applicable Australian Standards. Components from different formwork systems should not be mixed unless a competent person, for example an engineer, has authorised the component use. Variations to a design of a system should be checked and verified in writing by a designer, engineer or other competent person. Slips, Trips and Falls The design of the permanent structure affects the risk of injury from slips trips and falls (and from falling objects) during formwork construction and use. While often not reasonably practicable, permanent structure design measures that can reduce these risks include: reducing variations in the floor depth so it has one consistent depth. Formwork decks that are a consistent depth are easier to erect than variable depth floors and minimise the risk of injury. Deeper beams introduce ‘drop downs’ into the floor, creating trip and fall hazards and require more work to construct and strip after pouring beams designed to provide suitable access across the beam recess to prevent injury to workers from stepping into the form during construction reducing the number of columns required and where columns do exist, eliminating capitals and dropdowns, and reducing cantilevered floor sections. The design of formwork systems can also reduce the risk of slips trips and falls by providing adequate safe access and fall and falling object protection. Manual tasks The design of formwork systems can reduce the amount of manual handling required in formwork activity. To reduce manual handling risks use: precast columns and beams to minimise fixing reinforcement, erecting and stripping column formwork and pouring concrete on site - work activities carried out in a factory environment are generally lower risk table or flying forms—a large pre-assembled formwork and falsework unit often forming a complete bay of suspended floor slab, and modular formwork systems which are often lighter weight and eliminate the need for tasks like repetitive hammering. 3 JULY 2014 GUIDE TO FORMWORK Types of formwork The safety of workers erecting, using and dismantling the formwork should be considered when choosing a formwork system for a particular job. In particular consider stability, strength and the risk of falls, falling objects and manual tasks. The best proprietary systems have integrated safety features to help control the risk of falls and hazardous manual tasks. Traditional formwork systems are typically constructed on-site from timber or plywood and supporting elements like scaffolding. When using a traditional system, a standard formwork frame with a known tested loading capacity should be used wherever possible. Standard frames can minimise the risk to workers erecting and dismantling the formwork and handling and storing materials. Modular formwork systems are specially designed and manufactured off-site. Modular systems usually have proprietary formwork components and rated load calculations set out by the manufacturer and are often made from hardboard, plastics, steel and aluminium products. Most formwork systems use two or more materials, for example plywood facing to steel frames for wall panels. Modular systems are often lighter weight and require less physical effort than traditional systems. This minimises the risk of injury resulting from manual tasks. However because of their lighter weight, modular systems may be more susceptible to falling over when erecting the system due to factors like wind loading. Generally this will only be an issue before placement of the formwork deck on the modular system. To effectively control this issue the modular formwork system should be progressively braced in accordance with the suppliers instructions during its erection. Wall and column forms Wall and column forms should be designed to withstand wind loading before, during and after the concrete pour. The bracing and forms should not be removed from the cast element until it can safely withstand potential impact loads and wind loads. Lateral support can be provided to vertical elements in a variety of ways including horizontal and angled braces and structural connections to other parts of the building. A bracing element design should be completed by a competent person. The bracing element should also be able to resist both tensile and compressive loads that may be applied by the wind. Anchors for braces should preferably be cast-in type anchors or ‘through-bolts’ extending through both sides of the anchoring medium. Drill-in anchors of the following type may be used provided they are installed in accordance with the manufacturer’s instructions: Undercut type anchors that do not rely on friction to function. Expansion anchors of the high-load slip, torque controlled type. These anchors have a working load of at least 60 percent of the first slip load and are generally suitable for structural tensile loads. Coil bolts—the correct operation of coil bolts is greatly dependant on them being installed in accordance with the manufacturer’s specifications, for example drilling the correct size hole and applying the correct torque in concrete. Note: Some jurisdictions may not accept these types of installations, so check with your WHS regulator. Drill-in anchors should be installed in accordance with the manufacturer’s instructions. They should have their torque set using a torque wrench or other reliable method to verify the torque, for example a calibrated ‘rattle gun’. Written records verifying the setting torque for drill-in type anchors should be available at the workplace. ! ! 4 JULY 2014 GUIDE TO FORMWORK Access platforms Suitable access should be provided for wall and column forms and may include: mobile scaffolding purpose built access platforms, or elevating work platforms. Edge protection should be provided on the uploads/Ingenierie_Lourd/ guide-formwork.pdf