The Brohn Method

This method for the development of a sound, reliable and effective basis of an understanding of structural behaviour is based on the testing of three consecutive years’ entry to the Arup Graduate School in the early 1970’s (1,2).

Their performance in a test similar to that in the attached paper, was much less than expected with a mean score of 35%. Arup then commissioned David Brohn to develop a two-day training course to correct this deficiency.

This course, ‘Developing an Understanding of Structural Behaviour’ has been run continuously since that time for many of the UK’s and European structural consultancies.

The significance of the test results was finally recognised by the Institution of Structural Engineers in 2009 who set up a committee to promote the development of this skill in UK Universities. However, in what is a familiar outcome of committees, that objective was lost and what was a once in a generation opportunity to ensure that graduates had a basic understanding, was lost.

The failure of the academic community, with rare exceptions, to develop this skill is not all that surprising; it requires a sound and reliable understanding that can only be achieved with practice That does not fit well into the traditional syllabus.

But the overriding reason for the graduate’s failure, as the paper demonstrates, is that the reasoning required is not the ability to solve the typical approach in structural analysis; identify the algorithm and solve a linear sequence, but a sound understanding that relies upon a cyclic approach.

Because this skill is so critical in the design process, as the paper discusses, we have decided to establish a Certificate for the Brohn Method.

The key aspects of the Method

The method is deceptively simple, after all, graduates know what deflected shape and bending moments mean. But they consistently fail in the test, as the paper demonstrates.

The explanation for the failure is that it has not been explained to them that the solution must consist of the three parts to the solution. The reason for this that it is very easy to arrive at an incorrect solution and it is only by applying the checking procedures with the other two part of the solution that reveals the error.

It is for this reason that testing only one part, as in the IStructE Test, does not confirm that those tested have a sound understanding of structural behaviour.

Another explanation

In the 1960’s a team at UCLA, led by Sperry and Gazzaniga (3), were awarded the Nobel prize for their work on the mental activities of the left and right hemisphere of the brain. It is of course and immensely complex issue further explored by Blakemore (4) in his Reith lectures.

To perhaps oversimplify their conclusions, the left hemisphere, which controls the right hand, deals with analytical data whilst the right hemisphere with graphical data.

This is a working hypothesis as to why the graduates fail to solve such simple problems as the two test cantilevers; it is their difficulty in visualising the behaviour.

Around 8% of the population are left-handed, but in colleges of art, 25%, ie right hemisphere.

There is a useful way of establishing your preferences through the MBTI, Myers-Briggs Type Indicator.  There is a lengthy debate on this system in Wikipedia. The MBTI was established by a mother and daughter in the US, in the 1930’s. It was only later that the couple found that they had been duplicating the work of Jung, but his text ‘Personality Types’ had only been published in German.

This approach is much decried by modern psychologists as it is not based on the modern theoretical approach of contemporary systems. However, it is a useful basis for a discussion.

The results of the questionnaire type thus;

Introvert/Extrovert

INtuitive or Sensate

Thinking or Feeling

Judging or Perceiving

It is important to understand that the system shows your preferences,not your abilities.

The author is INTJ, Introvert, Intuitive, Thinking, Judging.

With many decades of experience as an academic/trainer I might appear to be an Extrovert. But that is just practice.

When I was first tested, my Intuition score was off the scale, and I recognised that this has been a lifetime preference. It also explains why I am hopeless at anything mechanical!

Thinking and Feeling have a sex bias; men tend to think, women to feel.

When I was first tested I was an academic and was a P, perceiving. When I was running QSE, I became J, judging because when you run a small business, you have to make decisions, regardless of how much information you have.

See www.myersbriggs.org

If you are highly Sensate, you may have difficulty in visualising. If your preference is for Intuition, you may find the Test easier than your colleagues.

But this is about trying to understand why you fail to provide the correct solutions.

Certificate of the Brohn Method

This will be arranged through this site and will be available in March 2021. This is aimed at graduates with more than three year’s design office experience who have already focussed on the development of this method, either by studying the text, ‘Understanding Structural Analysis’, (5) available from bookshops and Amazon or by attendance at the CPD training course, run either internally of by the IStructE CPD program, or the online course –

The Certificate will be awarded on completion of an online test, which will require the candidate to show the full three-part solution, as shown in the paper from the Bath University graduate and to show what internal checks were carried out.

This will be a difficult test, with a pass mark of 70% and a distinction over 90%.

Once you have signed up, there is no limit to the number of times you can attempt the test, but that number will be noted on the certificate.

A typical Test Question

This frame is statically determinate, but 90 % of all graduates tested over several decades produce the incorrect solution.

By applying the other two parts, it is immediately apparent what the correct solution should be.

Test Item
Typical incorrect solution
Most obvious check
Correct solution

Reference

  1. Brohn, D. M. and Cowan, J. (1977) Teaching towards an improved understanding of structural behaviour, The Structural Engineer, 55, 9-17.
  2. Brohn, D.M. and Cowan, J. (1977) Discussion on the paper ‘Teaching towards an improved understanding of structural behaviour’, The Structural Engineer, 55, 49-515.
  3. https://link.springer.com/article/10.1007/s11065-020-09439-3
  4. Blakemore, C. (1977) Mechanics of the Mind, Cambridge University Press.
  5. Brohn, D.M. (1986) Understanding Structural Analysis, New Paradigm Solutions Ltd