9 April 2019
WorkSafe ACT are investigating the circumstances of the collapse of formwork while a concrete pour was underway. An element of this investigation includes the use of propriety formworks systems. An examination of a large volume of these systems has identified irregularities in the manufacturing of these frames. Defects in some frames have been identified to include defective and non-compliant welding of structural components.
Defective welds that have been identified in propriety systems include issues with:
- inconsistent weld size
- lack of fusion
- toe shape (non-uniform weld)
- stray-arc (arc-strike).
PCBU’s have a duty to ensure the provision and maintenance of safe plant and structures. To ensure this PCBU’s are required to take reasonably practicable measures which should include facilitating an inspection of these systems by a competent person and any defective or deformed frames including welds must not be used until the faults are recertified.
Other elements of the investigation have identified limited testing of propriety systems in accordance with AS3610 restricts the use of systems in configurations outside of full assembly configuration the system is tested in. Different systems have considerably different working load limits therefore it is imperative that the working load limits are known, the configurations of the system are in accordance with manufacturers specifications and the full assembly is used in the same configuration the testing is undertaken with the load to be applied within the WLL capacity identified for the system.
PCBU’s must consider all reasonably practicable controls to manage the risk of a formwork collapse.
These controls include:
- Ensuring that a competent person must design the formwork to retain its shape and withstand loads such as reinforcing, concrete and other associated materials and the dynamic loads imposed by pouring, vibrating, the movement of people or plant or environmental factors such as wind and rain;
- Installing the formwork in accordance with the design and instructions from the designer - formwork should be rigid, watertight, braced and tied together to maintain position and shape during construction;
- Checking variations to the design and ensure they are verified in writing by the designer, engineer or other competent person;
- Not mixing components from different formwork systems;
- Putting measures in place (e.g. bracing), to prevent vertical support feet, on inclined surfaces, from slipping;
- Before loading with weight, ensuring that a competent person (e.g. an engineer with experience in structural design -certifying engineer) inspects and certifies completed formwork and its supporting structures meet the design specifications and are structurally sound;
- Placing concrete in accordance with the specified sequence and pour rate in order to maintain the stability of the formwork;
- Monitoring formwork as it is being loaded to check for signs of potential failure or collapse and to ensure vertical and horizontal movements do not exceed specifications; and
- Providing all workers with information and training specific to the formwork system, including:
- details of the formwork system, tasks, activities and components;
- design intention regarding installation, use, movement, alterations and dismantling;
- control measures to minimise identified risks; and
- how to inspect materials used in the formwork system.
The Safe Work Australia website provides useful information relating to Formwork. The links are provided below.
- Formwork and falsework guidance material
- Formwork guide
- Information sheet: Formwork falsework
- Formwork guidance material (ZIP)
This Alert contains information emerging during an investigation by WorkSafe ACT into the mentioned incident at the date of this report. The information contained in this report does not necessarily reflect the final outcome of WorkSafe’s views or proposed actions with respect to this incident. WorkSafe ACT does not warrant the information in this report is complete or up-to date and does not accept any liability to any person for the information in this report, or its use.
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