CROSS Safety Report
Further concerns about competence
This report is over 2 years old
A reporter raises concerns about competency, and the points raised demonstrate, says the reporter, a poor grasp first-principles on the part of many designers.
Key Learning Outcomes
For civil and structural design engineers:
A quality assurance system within your organisation, that includes the internal checking of calculations, can help prevent safety issues like this from occurring
Competent supervision of design by experienced personnel can allow less experienced engineers to develop a feel for what is the right solution
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A reporter carries out steelwork connection design for fabricators. This involves using the output of the consulting engineer responsible for the frame design and specification of joint force. They say that they commonly identify problems with the incoming design and one example is on a two-storey steel framed section, part of a larger building constructed using other means.
The initial design had columns lacking lateral restraint; ie carrying edge beams but not tied to prevent out of plane movement. The design was then changed to introduce curved edge beams. These were UB-section and had only simple shears specified at the ends of the beams.
The reporter pointed out that this was not stable and then not only were the beam end reactions changed to include torsions but the beams revised to torsionally stiff RHS sections. Even then the reporter had to point out that some of the torsional moments at the ends of the beams still were carried by unrestrained two storey columns. This is fairly typical of the errors seen by the reporter’s firm which often involve issues of:
These demonstrate, says the reporter, a poor grasp first-principles on the part of many designers.
Expert Panel Comments
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There are three generic problems that constantly recur:
reliance on computer output without a proper understanding of implications and significance
a failure to appreciate principles of stability either globally or in relation to members
the traditional spilt between the overall designer and the fabricator on connection designs
Even if the detail connection design is handed on, there is a responsibility on the main designer to assure that connection design is compatible with required overall performance and is feasible.
Structural engineering is a safety-critical profession and comments here could be similar to those given for the previous report in relation to competency. Clients must satisfy themselves as to the competency of the designers prior to appointment, and to the management procedures within the organisation, including competency of the individuals, the checking regime, the resource allocation and other relevant aspects. Whilst this example refers to structural steelwork it could well relate to materials of any type.
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