CROSS Safety Report
Steel portal frame erection
This report is over 2 years old
A reporter describes how a steel portal frame collapsed during its erection.
Key Learning Outcomes
For construction professionals:
Quality control and competent supervision on site can help to ensure that the structure is built in accordance with the design
Having a competent temporary works designer/adviser in place to supply an engineered solution can ensure all temporary works are carefully considered and planned
Verification of temporary works erection by a competent person who can oversee and coordinate the whole process can also ensure the works are installed correctly
Find out more about the Full Report
The Full Report below has been submitted to CROSS and describes the reporter’s experience. The text has been edited for clarity and to ensure anonymity and confidentiality by removing any identifiable details. If you would like to know more about our secure reporting process or submit a report yourself, please visit the reporting to CROSS-UK page.
The project described by the reporter involved the construction of a large span steel framed portal frame building. Longitudinal stability was provided by triangulated vertical side bracings and triangulated bracings in the plane of the rafters. The erection method statement had been based upon the principle that the first bay to be erected would be the bay containing the side and rafter bracings.
There would be temporary wire rope guys until the permanent bracings had been installed and fully bolted. A delay occurred in the delivery of the permanent bracings to the site but nevertheless it was decided to press ahead with construction and use the temporary wire rope guys to achieve longitudinal stability.
After erection of several bays of the structure had been completed a large quantity of purlins were lifted onto the roof. The eccentric load was sufficient to overcome the resistance to longitudinal de-stabilising forces provided by inadequately anchored guy ropes. The structure collapsed.
The eccentric load was sufficient to overcome the resistance to longitudinal de-stabilising forces provided by inadequately anchored guy ropes. The structure collapsed.
This happened slowly enough for those personnel involved in construction to move to safety. It was a near miss. This clearly illustrates the need to adhere rigidly to method statements and which should only be changed with the agreement of the originator or at least an accepted figure of authority who has sufficient technical knowledge to make decisions.
Expert Panel Comments
Find out more about the Expert Panels
Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.
Another example of the importance of temporary stability. Stiffness not just strength is needed for stability and guy ropes, even if strong, might well be too flexible to do the job properly. It is also the case that a vertical load applied eccentrically will cause lateral sway.
Submit a report
Your report will make a difference. It will help to create positive change and improve safety.
Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others.
No feedback has yet been published for this page.