Workplace Health and Safety Queensland released a health and safety alert following an incident last month where a six-tonne pre-cast concrete wall panel fell from the seventh floor of a building under construction.
The alert hopes to remind workers, employers, builders and designers of the risk of falling concrete elements attached to the perimeter of buildings under construction.
“This incident is currently under investigation and a number of factors may have contributed to the incident,” Workplace Health and Safety Queensland stated in their alert. “The panel had been attached to a floor of the building by abutting the inside face of the panels to the floor using two “L” brackets. The two brackets were welded to steel insert plates on both the pre-cast panel and the concrete floor. The design relied upon the weld integrity and the strength of the bracket for the panel to be supported – the panel was suspended from the brackets. Although two braces were also attached to the panel, these only prevented lateral movement of the top of the panel and failed as the panel fell.”
The safety regulator said it is difficult to give a justification for the use of welding to attach panel brackets to concrete wall panels, where welded connections are critical safety connections because of the inability to prevent panels from moving during the welding process; difficulty for the welder to insert the electrode at the correct angle and distance from the weld because steel plates were recessed below the surface of the concrete panel; difficulty applying the correct heat for sufficient weld penetration to the case in steel plates on the concrete panel; and lack of comprehensive inspection and testing process to verify the welds comply with the design engineer’s specifications.
Workplace Health and Safety Queensland said the use of welding for critical connections to secure concrete elements on building perimeters should not be done, particularly where the design relies on the welds for the panel to be prevented from falling off the building. It recommended using bolted connections between the panels, brackets and the building as a more reliable method than welding.
More information about this safety alert is available on Workplace Health and Safety Queensland’s website.