CROSS Safety Report
Failure of load test setup
This report is over 2 years old
A load test setup used to test a composite steel girder failed due to over estimation of the capacity of the supporting member.
Key Learning Outcomes
For construction professionals:
It is good practice to have a load test arrangement designed and assessed by a suitably qualified engineer to ensure the members can accommodate the test load
Find out more about the Full Report
Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others. If you would like to know more, please visit the reporting to CROSS-UK page.
A composite steel girder was designed to support the platform for a Metro Rail station, and it was decided to do a working load test on it at the fabrication yard before erection (Figure 1 & 2). Unfortunately, the load test setup failed due to over-estimation of the capacity of the Indian standard steel beam (ISMB) provided for supporting the girder.
An investigation into the failure found three contributory causes:
- A detailed 3D analysis simulated the design bearing load over the ISMB-300 member and it was found that the stresses in the member were more than three times greater than yield strength
- The design size of the elastomeric bearing pad was greater than the flange width of the ISMB300 so the bearing area was insufficient
- The main cause of the failure of the load test was the lack of proper stiffening plates
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.
Assuming that it was an overestimation of the strength of the supporting member then the lesson is that test rigs should be designed to the same level of detail as the piece being tested. Safe working loads need to be defined for the test rig, as often the tested piece may be significantly stronger/stiffer than expected and loading to deflection/failure criteria of the test piece can fail the rig.
As is so often the case attention to detailing is required. All elements on the load path need to be looked at - there is always a weakest point.
Share your knowledge
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.