#EpicFAILS 2 [Structural Engineering]

If you keep watching the Twitter feed above for a few seconds then it will update with news of buildings which are collapsing all over the world.

Thanks to Twitter, we can't escape epic failures of a structural engineering kind on our weekends either.

Last Friday, we summarised the failures of one building, one bridge and one walkway [click here]. Each of them were caused by a very unique set of mistakes and miscommunications.

It is undeniable that all of the structural engineering disasters which are covered here in Starting up an Engine[er] were preventable. The offerings which I have for you this week though, they stand head and shoulders above all others for one incredulous reason. Both Engineers and Contractors gave fair warning of their imminent failure in their present condition, or if the proposed alterations were carried out. Scandalous.

With out further ado, let me introduce you to three delinquents from the world of structural failures.


The Sampoong Department Store collapse, South Korea [1995]
#Killed [injured] - 501 [937]
Building Chairman - Lee Joon [The Sampoong Group]
This disaster carries with it a very large casualty list indeed. Sadly, due to bribery and corruption, the ill-fated construction project was approved by city officials in 1989, and then promptly collapsed 5 years later after a series of alterations which hastened the buildings demise. In reality though, the fate of this 5 storey structure was set only a year into it's 2 year construction programme.

The original reinforced concrete framed 4 storey, yes - 4 storey building was built to be a block of offices. Part way through the construction though, the buildings intended use was changed to that of a department store, and this involved the cutting away of a number of supporting columns. The main contractor refused, and was kicked off the site as a result. Relevant retrospective structural checks must not have been carried out by an engineer.  The corrupt city officials approved the design changes, and the building opened in 1990 - attracting over 40k visitors per day, up until 1995.

Later in it's life the building, the owners planned to build a 5th floor, which would house 8 restaurants. This time a different main contractor refused to carry out the project on the grounds that it was far too dangerous, since they believed that the original building could not support yet another floor. They were sacked and another contractor was found to carry out the works.

To top this all off [quite literally] the roof mounted air conditioning units installed to service the new restaurants, as it turns out weighted 4 times the safe loading limit for the roof structure.

The combination of column removal, poor workmanship, overloading, plant vibration and the re-siting of the heavy roof plant lead to the eventual collapse of the Sampoong Department Store and the loss of 501 lives.

Lee Joon was sentenced to 10.5 years in jail for criminal negligence and the President of the Sampoong Group at the time faced 7 years for accidental homicide and corruption. ALSO a number of city officials were jailed for corruption, due to accepting brides, concealing illegal changes and poor construction.


The Quebec Bridge Collapse, Quebec City, Canada [1907]

#Killed [injured] - 75 [11]
Structural Engineer - Norman McLure and Theodore Cooper
Bridge Contractors - Phoenix Bridge Company

This disaster is still considered the worst bridge construction accident of all time. It appears that after it was decided to extend the cantilever section of the the bridge, relevant checks were not made to the design calculations. Later, it was found that the structure was incapable of carrying the additional dead weight during the construction phase of the project.

When the cantilever section started to show signs of distortion, the local engineering team lead by McLure from their head offices, and supervised by Cooper, became worried and communicated their fears to the project team. At first Cooper denied that the problems were serious, but McLure had a hunch that the warnings were not being taken seriously enough. The construction company were approached and Phoenix protested that the beams were bent when they got them.

Eventually Cooper relented and telegraphed the Phoenix Bridge Company "add no more load to bridge til due consideration of the facts" and both engineers travelled to the contractors offices to confront them.

The telegraph was never passed on, and later that afternoon, the cantilevered section of the bridge collapsed into the St. Lawrence River, claiming 86 victims. 75 of those perished.


The I-35W Mississippi River Bridge Disaster, Minnesota, United States [2007]

#Killed [injured] - 13 [145]
Structural Engineer - Jacobs Engineering [Sverdrup & Parcel]
Safety Inspectors / Analysis - URS Corporation

The collapse of the I-35W Mississippi Bridge was predicted by the computer analysis of the bridge before the event - by the URS Corporation. The bridge was scheduled for replacement in 2020 and temporary reinforcement right up until the last few months of it's life.

Unfortunately the engineers report, even though stating the bridge to be 'structurally deficient' for modern day loadings [which happens to be overloaded by 20% - between 2007 and the year of it's construction in 1964], critically the report also concluded that the bridge had met with minimum tolerable limits. This conclusion pushed the scheduled reinforcement back in lieu of periodic safety inspections, and eventually set the scene for a catastrophic collapse during rush hour one morning in August.

After a long investigation, the design was eventually found to be flawed, and law suits were raised against the design engineers and the engineers responsible for the safety inspections and analysis.

This represents another horrible example of us engineers not being able to communicate our fears with enough gusto to help prevent potential disasters.

I mentioned in a past post that I had stopped work on an entire building project due to a 'gut feeling' that I had. I was still an assistant engineer at the time, and responsible for the engineering works to a 4 storey load bearing masonry shop, in a busy market town in Norfolk.

A large number of walls and tying floors had been earmarked for removal, to make possible a giant conversion of the upper 3 floors above a supermarket into 'upmarket' flats. The senior engineer and I had spent a lot of time working through how to phase the demolition and reconstruction of the walls and floors, and therefore retaining enough of the structure to prevent instability during construction.

We issued our instructions along with the engineering drawings and calculations. A few months along into the demolition process, the builders were falling behind programme and stepped up their efforts. This included a decision to depart away from our engineering method statement.

I turned up on site our of the blue [just passing by], and whilst I stood amongst the masses amounts of construction workers busily going about their business, I reviewed the gaping holes where the walls once stood, and started to feel sick. I quickly informed the site manager to stop work and contacted the engineering director. We eventually had to survey the whole building and formulate a new plan to progress the works.

It was a sunny Friday afternoon, next to the coast. The shop car-park was full and there were atleast 100 workers on site that day.

Next week I will continue the theme and summarise my thoughts on 3 more engineering disasters.

If you have spotted any engineering project which is suspiciously lack lustre or feel under pressure not to spend enough time on a project which deserves it, then please follow this link to the CROSS and SCROSS structural safety website. There you will find advice on how to report your findings.

Please don't have night-mares.


Engine[er]