It can be said [I hope] that all of the engineering disasters spoke of in this blog thus far are of importance, and study of them will help us to understand further the historic and modern day pitfalls of structural design. They teach us many unique lessons about the potential problems within the design process, communication of design and the coveting of too much confidence in ones abilities. If we can take any lesson from the recent blog posts, that will be to expect the unexpected, and to seek help when you are plainly out of your depth - in an engineering capacity that is.
Fame or infamy are the natural by products of people, endeavours or instances in history which have meaning or can be defined by perhaps being the first to exhibit a particular behaviour or purpose [e.g. the tallest building]. By definition they stand-out, like a beacon of light, a celebration of being the best or a warning to all others to pay heed.
This week I'd like to speak of 3 engineering disasters which had historically defining effects upon our industry, they were failures which brought about very real changes to good design practice, building codes and the regulations which we all adhere to today.
To begin us off this week I would like to introduce you to the KING of building collapse case studies:
Ronan Point Building Collapse, London, UK [1968]
#Killed [injured] - 4 [17]
Contractor - Taylor Woodrow
Building System - Larsen-Nielson [large precast concrete panels]
This disaster has been very well covered in institution presentations, and research papers - all of which are obtainable from the IStructE website. It of course such an infamous structural disaster that it deserves a prominent place on our list of historic failures. The disproportional failure of this building is what set's it apart from all others.
The disaster was caused by a gas explosion, which occurred at the south east corner, on the 18th floor of this 22 storey block of flats. The disproportionate amount of damaged which then ensued, was enabled by the construction method used, and the level of workmanship involved [allegedly].
The method of construction, which was only initially intended to be made available to the construction of buildings less than or equal to 6 storeys in height, was chosen because confidence had grown in the system.
It was made abundantly clear by the high profile expert and structural engineer - Wilem Frischmann that this method of construction could be extremely dangerous for the inhabitants if such an event [like a gas explosion] were to take place. Wilem raised his concerns before the collapse in 1968.
As a direct result of the collapse and subsequent report [written by Wilem] that 9+ blocks of flats of similar construction, which contained a piped gas supply and were found NOT to be able to withstand a simulated 5psi explosion without a disproportionate amount of damage - were demolished.
Most importantly, a change in legislation and updating of Part A - of the building regulations occurred which detailed restrictions and amendments to deal with the issue of disproportionate collapse.
Tacoma Narrows Bridge Collapse, Washington, USA [1940]
#Killed [injured] - Tubby[the dog] [0]
Lead Structural Engineer- Leon Moisseiff
The Galloping Gertie. This has been an incredibly important case study ever since it's infamous failure. As a result of the collapse [which was famously captured on video] structural engineers the world over were forced to consider a whole new dynamic effect on the design of the bridge decks - aeroelastic flutter.
Again, as one would expect, there has been a great many industry and institutional presentations which have covered the reasons behind the failure of this both famous AND infamous bridge.
So why continue to regurgitate the same evidence? Well, apart from the aforementioned aeroelastic flutter, there was another very important lesson to be learned [or resurrected]. One which is has been repeated and threatens our self stylised position as chief protector of society, and practitioner of science for the benefit of mankind... and it goes a little something like this...
"The Tacoma Narrows bridge failure has given us invaluable information...It has shown [that] every new structure [that] projects into new fields of magnitude involves new problems for the solution of which neither theory nor practical experience furnish an adequate guide. It is then that we must rely largely on judgement and if, as a result, errors, or failures occur, we must accept them as a price for human progress" Othmar Ammann
Fame or infamy are the natural by products of people, endeavours or instances in history which have meaning or can be defined by perhaps being the first to exhibit a particular behaviour or purpose [e.g. the tallest building]. By definition they stand-out, like a beacon of light, a celebration of being the best or a warning to all others to pay heed.
This week I'd like to speak of 3 engineering disasters which had historically defining effects upon our industry, they were failures which brought about very real changes to good design practice, building codes and the regulations which we all adhere to today.
To begin us off this week I would like to introduce you to the KING of building collapse case studies:
Ronan Point Building Collapse, London, UK [1968]
#Killed [injured] - 4 [17]
Contractor - Taylor Woodrow
Building System - Larsen-Nielson [large precast concrete panels]
This disaster has been very well covered in institution presentations, and research papers - all of which are obtainable from the IStructE website. It of course such an infamous structural disaster that it deserves a prominent place on our list of historic failures. The disproportional failure of this building is what set's it apart from all others.
The method of construction, which was only initially intended to be made available to the construction of buildings less than or equal to 6 storeys in height, was chosen because confidence had grown in the system.
It was made abundantly clear by the high profile expert and structural engineer - Wilem Frischmann that this method of construction could be extremely dangerous for the inhabitants if such an event [like a gas explosion] were to take place. Wilem raised his concerns before the collapse in 1968.
As a direct result of the collapse and subsequent report [written by Wilem] that 9+ blocks of flats of similar construction, which contained a piped gas supply and were found NOT to be able to withstand a simulated 5psi explosion without a disproportionate amount of damage - were demolished.
Most importantly, a change in legislation and updating of Part A - of the building regulations occurred which detailed restrictions and amendments to deal with the issue of disproportionate collapse.
Tacoma Narrows Bridge Collapse, Washington, USA [1940]
#Killed [injured] - Tubby[the dog] [0]
Lead Structural Engineer- Leon Moisseiff
The Galloping Gertie. This has been an incredibly important case study ever since it's infamous failure. As a result of the collapse [which was famously captured on video] structural engineers the world over were forced to consider a whole new dynamic effect on the design of the bridge decks - aeroelastic flutter.
Again, as one would expect, there has been a great many industry and institutional presentations which have covered the reasons behind the failure of this both famous AND infamous bridge.
So why continue to regurgitate the same evidence? Well, apart from the aforementioned aeroelastic flutter, there was another very important lesson to be learned [or resurrected]. One which is has been repeated and threatens our self stylised position as chief protector of society, and practitioner of science for the benefit of mankind... and it goes a little something like this...
"The Tacoma Narrows bridge failure has given us invaluable information...It has shown [that] every new structure [that] projects into new fields of magnitude involves new problems for the solution of which neither theory nor practical experience furnish an adequate guide. It is then that we must rely largely on judgement and if, as a result, errors, or failures occur, we must accept them as a price for human progress" Othmar Ammann
Do we really?
Alfred P. Murrah Federal Building Bombing, Oklahoma, USA [1995]
#Killed [injured] - 167 [782]
Construction Method - Insitu Concrete Frame and Shear Wall
Another saddening event which was influential in changing the way we as engineers design reinforced concrete buildings above 5 storeys, and the analysis of potential blast damage.
The blast resulted in a maximum 10,000 psi blast into the nearest structural column, all the way down to a minimum of 9 psi to the upper west corner of the building.
The total of 4 columns collapsed due to the immediate blast loading, and resulted in the destruction of almost half of the floor area. Many lives were tragically lost.
Due to the effects of the upward direction of the blast wave, many of the adjacent floors were subjected to uplift. This was a load case not adequately catered for in the design and detailing of the reinforced concrete floors. Disproportionate collapse took care of the remaining upper floors.
This weeks stable of engineering disasters were once again aimed specifically at the art of structural engineering. None of the above case descriptions are meant to be extensive - a mere 'taste' of the event, with perhaps a personal opinion woven into them too.
The stand out feature of these disasters shown here on this post are to do with the journey into the unknown.
The Tacoma Narrows Bridge. Longest spanning suspension bridge in the world when completed. Ronan point, over confidence in a new building system, pushed way past it's originally intended limits for storey heights. The A.P.Murrah Federal building. Long spanning reinforced insitu concrete moment frames, with little to no redundancy incase of explosive removal of essential structural support [in this case - 4 columns].
At the time, each example above pushed structural engineering further into the unknown. An invitation to unknown loading conditions, just waiting to jump up and give the engineer a wake-up call. Again, many lives lost as a result.
Have we learned enough? Only time will tell.
Next week we will have our final 3 #EpicFAILS. Until then, please do not have nightmares.
Engine[er]
![Starting up an Engine[er]](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_48ubt0myJl9Kc2av_Yix8HwEpZTit9DLMrmiRI2LjDYLbqNtxNz6VTsBNTgpDxOGErtF-SRLInkC-wRWFeM-LRL0N0VvpgtHxCBKGnpQ1CZBb5-wXP76Y-of8pZkYpAOR7iTm1OOE6c/s435/newblog.jpg)
There was another bridge which went in a similar manner but this one had cars on it. So one should have learned from the other I guess...
ReplyDeleteAbsolutely! Which bridge was that?
DeleteI was under the impression that the Ronan Point disaster was responsible for considerations of progressive collapse, and necessary redundancy to make the structure robust.
ReplyDeleteSince my childhood, my dad retells the story of how had to redesign an entire project when the amendments came in. So many stories I cannot remember the details, but also there was need to design for the deliberate sabotage of buildings, and underground railway stations (Manchester, London). To do with terrorists attacks (eg. IRA, Palestine).
So I never considered the Oklahoma building as providing anything new, nor the world trade center (WTC). The WTC was built after Ronan Point, and still during an era of terrorism.
From Holmes wind loading of structures: Brighton Chain Pier England (1836), and Tay Bridge Scotland (1879) all failed prior to the Tacoma narrows bridge (1940). Then there was the Ferry Bridge cooling towers UK 1965 another failure to understand fluid dynamics.
So more along the lines of lessons learnt, not fully understood, not fully passed to next generation, nor communicated around the world.
Hi Steve. Thanks for your comments. Yes I agree, progressive collapse was reconsidered in the wake of Ronan Point. It is a shame that not all the lessons have been learned though.
DeleteIf you think about it, both disproportionate and progressive collapse would have been possible since day one in design of structures. So why did we have to experience the disaster before anything was done about it...?
I guess complacency. Typically goes: We've been doing it this way for 30 years without a problem, so why change? Or the classic example from Karl Popper: All swans are white? Except in Australia where they are black.
DeleteWe accumulate evidence that a structure is adequate based against preconceived notions of adequacy. We don't consider the alternate hypothesis that it is not adequate and seek evidence to demonstrate such point. Dan Quo's Applied Science blog discusses Popper and failures: though I disagreed with him, concerning that designers follow the Popper approach.
The concept of quality robust design in manufacturing is a lot closer to Popper than traditional design. It directly considers variation in all its forms and throughout life of a product: the design process, manufacturing process, operation and maintenance. Mere compliance with regulations is not good enough: for something to be quality robust. Design moves away from considering point values, to operating range. Doesn't just consider quantitatively but also qualitatively.
Getting resistance greater than the design load is not the real issue: for the assumed design load can always be exceeded. The important issue therefore, is when the structure or other product fails: how does it fail and what hazard does it pose? Is there some way we can control the failure so that it poses less of a hazard? So need to carry out FMECA. Not something which is routinely carried out for buildings.
Cool comments Steve, thanks for posting.
Delete