Forensic Engineering and Learning from Mistakes
If you Google “World’s Funniest Engineering Fails” you’ll see an array of ridiculous images – doors that lead out onto thin air, windows at strange angles, balconies that can’t be reached from inside the building and stairs that lead nowhere.
The truth is, these aren’t failures in engineering and they are not even all that funny, beyond perhaps a little chuckle at how on earth anyone managed to get that far into a project without realising their error.
When engineering failures happen, this can result in buildings collapsing with real risk of injury or death to anyone present at the time. This means that even minor failures must be investigated so that lessons can be learnt and similar errors avoided in the future.
What is Forensic Engineering?
When we are brought in to take on a forensic engineering role, we will first of all carry out an analysis of the situation. We’ll then speak to the engineers involved and work with them to solve the problem. It’s important not to embarrass the original engineers so good communication and cooperation to understand the issues is important.
In a recent case we were brought in to investigate a rear extension where too much cracking of the walls was occurring.
A picture frame had been put in to support the walls above while removing the rear wall of the property, but we found that the connections in the corners of the picture frame were not adequate. These connections needed to be strengthened to give greater fixity and support, and this solved the problem. Below is an example of a Finite Element Analysis (FEA) of a connection that we checked that failed.
Below is a FEA of an alternative connection that we did that provides adequate moment resistance for a picture frame.
Prevention is better than cure
Of course, it is always best to come up with the right structural solution in the first place, but we will work on finding the most economical solution to the problem.
With similar projects where we are involved from the start, we have our own approach to picture frames and foundations, enabling the picture frame to support the load above without any issues and reduced chance of settlement and cracking.
The importance of forensic engineering
Certain high profile cases have had a big impact on design codes, as in the well-known Ronan Point case.
This was a newly opened residential tower block in Canning Town that suffered a major collapse as a result of a gas explosion. In May 1968, resident Ivy Hodge lit her stove for a cup of tea and sparked a gas explosion in her corner flat that blew out the load-bearing flank walls.
Although Ivy was uninjured, and her stove survived the blast, the collapse killed four residents and injured 17. This was despite the fact that the three of the four flats above Ivy’s were unoccupied at the time.
The collapse of the entire corner of the tower was disproportionate to the event that caused it and led to an amendment to the Building Regulations in 1970 covering “disproportionate collapse”. These regulations specifically cover pressures that may be caused by wind forces, explosions, vehicle impact and seismic shifts.
Ronan Point was initially strengthened, but activists believed it was still unsafe and it was eventually evacuated and forensically demolished in 1986. As they took it apart, engineers found cracks in the concrete of the lower floors, where it had been point loaded. It was alleged that extra pressure on these points, such as during the Great Storm of 1987, would potentially have led to the building’s collapse.
Forensic engineering has a valuable part to play in both putting things right and in learning from mistakes. Please do get in touch if you need assistance with this kind of project.