The Cost of Ignorance in Structural Engineering

From the seven ancient wonders of the world, the only one left standing today is the Pyramid of Khufu in the Egyptian desert. Any man-made environment is destined to vanish eventually, but we are convinced that buildings will stand forever. When some do collapse or suffer some type of performance failure we are surprised and concerned; we want to know what went wrong and why. This was particularly true during the recent collapse of a roof at a mall in Elliot Lake, Ontario (see below).
From an insurance point of view, one of the main concerns is determining who should cover the costs associated with the failure.  In order to answer this question, one needs to determine the true cause of the failure. This can be a daunting task and experts’ assistance is often required to unveil all the factors involved in a failure.

Structures come in various shapes and serve many different purposes. They are built of many types of materials and have to resist many kinds of loads. These loads can originate from various sources and contain many uncertainties. In order to determine why a structure failed, an understanding of how the various elements of the structure work and interact with each other is necessary. Which element failed first and why? How did the failure of that element result in the failure of the rest of structure? Was the failure caused by excessive loads, design flaws, faulty material, ground movement, poor construction, inadequate maintenance, a combination of these, or an unforeseeable circumstance?

After any loss, one question that both the insured and the insurer want to answer is: Can the structure be repaired or does it have to be demolished? The easiest and the most straightforward response will be “demolish and rebuild.” In our experience this approach is often proposed despite the building being a good candidate for repair at substantially reduced costs and with a fraction of business interruption time.

One typical reason for not considering the repair approach can be a lack of expertise in damage assessment and evaluation of the remaining structural capacity. This is how ignorance can be costly. To properly evaluate a damaged building requires deep-seated knowledge, thorough investigation and sound engineering judgment, which, except for the simplest of structures, only an experienced expert can provide. While involving an expert may add some additional costs for the investigation, it can potentially save a significant amount of money as the expert will be able to maximize the utilization and rehabilitation of the damaged building.

The failure story has an often ignored side: the pre-existing condition of the structure. Imagine that a truck impacts an industrial steel frame building and destroys two bays. The clean-cut scenario is that the building owner claims the whole repair cost and the truck insurer pays. However, the reality is likely much more complicated than that.

Consider the following possible scenarios regarding the pre-existing condition of the building prior to the vehicle impact: What if the steel frames had been heavily rusted and the owner had planned to replace them in two years anyway? What if the frames and their connections had not been designed to the applicable codes/standards originally? What if the building construction was faulty so that it was only a matter of time before deficiencies were detectable, and these deficiencies just happened to be materialized during impact? What if the owner had added extra loads (e.g. roofing, cranes, walls, extra office spaces, etc.) in excess of what the building was originally designed for, thus, the impact only initiated the failure (but did not cause it)?

As often is the case, whoever touches the structure last may incorrectly foot the entire repair bill. In these cases there are possibilities for subrogation and mitigation of the costs that would be lost unless all the relevant facts are discovered and considered objectively by an experienced expert.

Among the many potential causes of a structural failure, inadequate maintenance requires special attention, as maintenance is often neglected since the need is not always readily obvious. Proper maintenance becomes critically important for large buildings and aging infrastructures as negligent maintenance could result in catastrophic losses.

The following are just a few examples of recent large losses in which the lack of a proper maintenance program may have caused or contributed to the loss. In 2007, the collapse of the Mississippi River Bridge (HW I35) killed 13 people, injured 145, and caused a direct loss of over $300 million and a lot more indirect losses. A photograph taken four years before the bridge collapse showed bowed gusset plates which had gone unnoticed at the time. The same plates eventually failed and caused the entire bridge to collapse.

In June 2012, the roof of a mall in Elliot Lake, Ontario collapsed, killing two people and trapping dozens. The roof had shown signs of excessive water leakage during the previous decade; furthermore, a piece of concrete from the roof had fallen through the ceiling at a mall restaurant just one year before the collapse near to the failed section.

More recently, in December 2012, concrete ceiling panels inside a tunnel section in Tokyo, Japan collapsed, killing nine people. Preliminary reports pointed to undetected decay in the fixtures that had held the concrete panels to the roof.

Although structural failures often occur suddenly, in most cases there are many signs of impending failure before it actually happens. Proper maintenance and inspections can reveal signs of deterioration before it becomes too late. The U.S. government plans to spend over $1 trillion over the next decade on existing infrastructure such as roads, waterways and power lines to prevent their deterioration. The situation of Canadian infrastructure is not any better; however, such a plan does not exist here. Years of neglecting proper maintenance and current financial belt-tightening are causing vital repairs to be pushed dangerously down the priority list.  

One thing of particular relevance to the insurance industry is the claimed damages relating to losses involving aging infrastructure. For instance, a small piece of concrete that falls off a bridge and cracks a car windshield may be a sign of a much bigger problem (e.g. the QEW/Gardiner in Toronto, Ontario). Such a structure should be checked at the proximity of the incident to reduce the risk of a large loss in the future as well to explore the potential subrogation avenues. Further, if a loss occurs that specifically causes damage to the infrastructure (e.g. a piece of heavy equipment on a trailer strikes a bridge), be sure to evaluate the previously planned remediation for the structure. We have seen many cases in which the owner of the infrastructure attempts to recover, from the insurer of the trucking company, the cost of repairs that were slated to occur in any event. This is where an expert who has a deep understanding of the nature and life-cycle of structures can be of great assistance.

When a structure fails, especially if it involves a large loss, the general tendency of the insurance industry is to retain a large structural design firm to investigate the origin and cause. Unless that specific firm has an in-house forensic group, this is not always the best choice.

Large failures are usually complex and multi-faceted and, in many cases, the structural failure is only the symptom of other issues in the building. A typical structural designer often looks at the structural elements, but cannot see the overall picture of the failure. This is where a multi-disciplinary forensic firm, a group of people specialized in different aspects of the building and its construction, can investigate a failure from various angles to find out all the involving facts and pinpoint the true probable cause(s).

As the saying goes: “To a hammer, everything looks like a nail!” (Individuals sp
ecialized in one specific area may have the tendency to relate everything back to their area of expertise and ignore other possible aspects outside of their expertise).

Dr. Farhood Nowzartash, P.Eng., is a structural engineer at Giffin Koerth who has wide-ranging structural expertise, from large-span steel sports stadiums to high-rise reinforced concrete buildings. He combines academic strength with real world design and construction expertise. For more information on Farhood and Giffin Koerth, please go to www.giffinkoerth.com