Precast panel structure
13 May 2019
This Safety Alert has been developed to attention to the construction industry, builders and designers of the risk of collapse of concrete panels during the installation process.
The collapse of any concrete panel, even a small one, can have catastrophic consequences for workers or the public. The risk of panel collapse exists throughout the entire construction process, not only during the panel erection phase. The risk of collapse must be managed until the concrete panel is effectively tied into the building’s permanent structure. Erecting precast concrete panels, using mobile plant around the panels and altering or removing temporary bracing is always high-risk construction work and will require safe work method statements (SWMS) to be prepared and followed.
Precast panels are used within the exterior and interior walls. By producing precast panels in a controlled environment (typically referred to as a precast plant), the precast panels are afforded the opportunity to properly cure and be closely monitored by plant employees. Using a precast panel system offers many potential advantages over onsite casting. Precast panel production is typically undertaken at ground level which assists with the control of safety aspects during the casting process. There is greater control over material quality and workmanship in a precast plant compared to a construction site.
The precast concrete panels are being extensively used for both residential (low and high rise) and commercial constructions because of their favourable attributes. The efficiency, durability, ease, cost effectiveness, and sustainable properties of these products have brought a revolutionary shift in the time taken in construction of multi-storey structures.
There are many different types of precast concrete forming systems for architectural applications, differing in size, function, and cost. Precast architectural panels are also used to clad all or part of building facades or free-standing walls used for landscaping, soundproofing, security walls, and some can have prestressed concrete structural elements. Stormwater drainage, water and sewage pipes, and tunnels make use of precast concrete units.
It is essential that each structural component be designed and tested to withstand both the tensile and compressive loads that the panel will be subjected to over its lifespan. It is also essential that designs of Precast panels meet practical guidelines of construction and building design. If changing the design of the building panels is required to meet standards and safety of the overall structure, this should be undertaken prior to installation. There must be a process in place to manage these changes so the design parameters of the panel are not exceeded, and the design of the structure is not compromised.
In Australia, workers have been seriously injured or killed in a concerning number of incidents involving precast panels during the installation and final prop removal stages.
It is important to note that those involved in the installation of Precast Panels must be fully informed of the methodologies of each stage, in a planned and chronological order. It is important that each step of the installation process is understood and that the roles and responsibilities of each worker is clear and communicated to all involved. Under no circumstances should anyone perform a duty, such as removal of props, without being appropriately trained and authorised to do so.
The installation of precast panels is a high risk construction work activity and requires the completion of a safe work method statement (SWMS). It is imperative that the SWMS is strictly followed and the planned process is not deviated from without appropriate planning and documented variations made to the SWMS.
Mitigating the risks
Only competent, suitable qualified, trained, instructed and supervised workers are to participate in the installation of precast panels. All persons are to be suitably inducted into the SWMS and possess an intimate knowledge of the work they are undertaking prior to commencing any high risk construction work.
If you are a person conducting a business or undertaking (PCBU) involved in the installation of precast panels you must ensure a chronological system of:
- an appropriate safe system of work is in place;
- any system used for attaching precast elements to building perimeters is to undergo a comprehensive design process by a competent professional engineer, including a signed design verification statement to relevant design standards;
- a system for verifying that the design engineer’s instructions have been followed should be provided. This will include inspection and sign-off by a competent person;
- the work is planned, including the development of an erection plan (with an appropriate lifting device) that is appropriate to the task and panel type;
- the work is monitored and supervised by a competent person who is experienced in concrete panel erection;
- a site-specific SWMS is developed and followed. The methodology must minimise the risk to workers during the erection with a planned panel installation sequence that is appropriate to the individual task, is available onsite and has all workers inducted into it.
- workers are suitably trained, competent and qualified to perform the task;
- workers performing licensed roles possess the required high-risk work licence for the task they are performing; and
- there should be a documented change management process in place to control and record any changes to the design or methodology.
In the coming weeks, WorkSafe ACT will be developing and implementing a compliance program covering current construction sites installing pre-cast panels. WorkSafe inspectors will be conducting onsite inspections of processes during precast panel installations including design aspects and any modifications, installation, final stages of prop removal and other potential hazards associated with precast panels.
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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