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CROSS Safety Report

Unconnected steel beam connection

Report ID: 646 Published: 1 October 2017 Region: CROSS-UK

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Overview

A reporter describes how they came across a completely inadequate steel connection while attending site for another matter.

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

For civil and structural design engineers:

  • This report highlights the potential value of visits by the design team who may (as on this occasion) identify a problem. If you are unable to attend site, consider asking the contractor for site photos of the installation of critical structural elements

For steel fabricators:

  • Structural steel should be CE marked and purchased from reputable steel manufacturers who meet the appropriate manufacturing standard
  • It is good practice to have a quality control procedure in place to inspect incoming steelwork to ensure it meets the required standard
  • The British Constructional Steelwork Association (BCSA)/TATA Steel publication Steel Construction - CE Marking is a useful document and provides guidance on CE marking

Full Report

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A reporter came across a completely inadequate steel connection. While the endplate had been welded to the supported beam, and the flange plate has been welded to the endplate, the flange plate has only been tacked to the supporting beam (Figure 1). These tack welds could also be defective as the paint was not stripped prior to welding, so the welds may not have taken, or be porous.

Image
Figure 1: unconnected steel beam connection

This astonishing error was only discovered by God’s good grace, says the reporter, when they were on site for something else and happened to walk underneath it. There were several issues with the beams in question on site:

  • Originally the beams had been fabricated the wrong size

  • They were then installed upside down

  • They were then site modified to move the flange plates, then modified again because these had been put in the wrong place

  • Then redrilled on site because the bolts did not line up, and finally welded in place

These errors came about in part because (not for want of multiple warnings on the reporter’s part) the contractor used an inexperienced and non-CE marked steelwork contractor who was unused to structural steelwork, had no design capability, and had no welders with site welding certification.

If contractors were aware of the law regarding structural steelwork, or even if building control enforced it, we would not have been in this position. Structural engineers can only do so much especially if their advice is being ignored.

If contractors were aware of the law regarding structural steelwork, or even if building control enforced it, we would not have been in this position. Structural engineers can only do so much especially if their advice is being ignored

Expert Panel Comments

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Once again, the diligence of a reporter has averted what could have been a major incident demonstrating again the importance of experienced personnel inspecting what is happening on site. Were this done more often the risks of collapse would be reduced. Assuming that the matter was raised and dealt with on site at the time, the remaining issue appears to be that the builder did not use CE marked steelwork.

Mandatory CE marking

CE marking of fabricated structural steelwork delivered to site became mandatory on 1 July 2014 under the Construction Products Regulations, which place legal obligations on members of the supply chain, including manufacturers, distributers, and importers. 

Specifying the right Execution Class

BS EN 1090-1 is the harmonised standard that covers fabricated structural steelwork. The client or main contractor that engages the steelwork contractor should carry out due diligence before appointing them and ensure that they engage a steelwork contractor with an Execution Class equal to that required for the project.

The design engineer is responsible for specifying the Execution Class for the structure as a whole and for components and details they have designed in compliance with BS EN 1993-1-1 – “Design of steel structures – General rules and rules for buildings".

Further information on this can be found in a very useful document “Steel construction CE Marking” published jointly by TATA and BCSA.

Trading Standards is the enforcement agency in the UK and given the undoubted seriousness of the example, should have been notified.

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