We all know the meaning of the word “failure”. Based on the context though, this can mean a lot of different things. For every profession out there, it takes a different set of meanings. Here we will of course focus on civil engineering and construction. Although this post was written in plain English for nonengineers to follow, it is hoped that it will also be a good refresher, an interesting read or even reference for many engineers as well. Pay attention to the links given here, which are continuation to specific fields in civil engineering, so by saying “this post”, the author means also the linked posts from here. Including them all here in a single post would not be practical and easy to follow.

When we discuss failures, it would be appropriate to first mention a very fundamental concept: In whatever we design, there is the serviceability limit and then there is the ultimate limit. Serviceability limit is the point up to which a system maintains its ability to effectively serve its intended duties. When this point is reached, the system can still withstand the demands from it, but beyond here it will no longer be fit for our use efficiently / effectively or at all. Ultimate limit is when the element or the structure can no longer tolerate even a small increment of demand and will totally fail / collapse. These limits are all given and described in detail in relevant codes, to ensure public comfort and safety. In a way, we can think that the entire body of a code is actually a set of instructions to guide engineers to design systems that will not fail when they are supposed to serve.

And then there is also the failure modes of a system. A failure mode is a certain way that a system can fail. A bridge, a retaining wall, even an anchor… all of these can fail in a number of different modes. In this post and the linked posts about failure from here, we will list a lot of failure modes. Not only for just strength criteria there can be different failure modes, but also there are almost always multiple criteria of failure for a given system or structure. For example in addition to strength failures, failure may also mean too much deformation than what we want. For example, if the slab of the room that you are in right now sagged so much that you could see it with your bare eyes, you would not feel comfortable to be there at all, and we consider that slab failed, even though that slab might continue to safely carry you and the furniture over it for another hundred years. Or if you are at one of the top floors of a skyscraper and it swung “too much” during strong winds, again, it would not be comfortable for you, even if structurally it may perfectly be fine. A highway is considered failed, if it caused frequent accidents at a certain spot, or when it cannot handle the traffic load that it is supposed to handle. A sewer system is considered failed, if it leaked or couldn’t meet the flow demand and so on… All these failure criteria are well defined in relevant codes and guidelines.

There are thousands of ways things can fail in civil engineering and construction. What is discussed in here and the linked posts are just some handpicked background information and some common items to give the readers an idea or to refresh minds of others who already know and serve as reference.

Civil engineering has five main branches, which are Structural, Geotechnical, Transportation, Water Resources and Construction – at least this is the common way of categorizing it. While discussing failures it makes sense to follow this categorization, however we will not make a separate construction section but give construction aspects, together with their design aspects in all first four categories. Below we only make a brief introduction of each category, and then link to their respective posts which contain more in depth articles.

Structural Engineering Failures:

Structural failures are probably the first thing that comes to mind, when we say “failures in civil engineering”. Structural members and structures themselves can fail as a result of thousands of different reasons, but all can be narrowed down to several main categories such as yielding, buckling, rupture and a few more. See our post structural engineering failures, as a continuation of this paragraph. But before that, if you are not an engineer and want to familiarize yourself with the most fundamental concepts in structural engineering, you can also check our post in Construct Magazine, summary of structural engineering fundamentals.

Geotechnical Engineering Failures:

Geotechnical failures often affect a structure as a whole, and therefore often serious and very costly to fix. Geotechnical failures mostly stem from inadequate bearing strength / foundation system, but other failure modes also exist such as including but not limited to expansion of soil, freeze thaw action, liquefaction. Tunnels, retaining structures have their own unique set of geotechnical failure modes. Also see our post geotechnical engineering failures, as a continuation from here.

Transportation Engineering Failures:

Transportation related structures make up a significant part of all structures. Highways, tunnels, bridges, all fall under transportation engineering (the structural design of a bridge or tunnel is by structural engineers specialized in these structures, but the high level design such as overall placement, specifications and capacity fall under transportation branch). These structures are links in our infrastructure and therefore very critical. They are usually built with higher importance factors, designed to less frequent, stronger earthquakes. Also see our post in ConstructMagazine.Com, transportation engineering failures.

Water Resources Engineering Failures:

Water resources engineering is one of the main branches of civil engineering. Dams, coastal structures, sewer and storm drain systems fall under this branch. Similar to transportation branch, the structural design are done by specialized structural engineers but the higher level design, placement, capacity calculations fall under water resources branch. Similar to transportation branch, these structures have high importance factors. Also see our post in Construct Magazine water resources engineering failures.

Construction Failures:

A good design will mean little, if the construction of that design is poorly performed. Construction branch of civil engineering differs from the four we listed above because while the previous ones deal with the design, it is the construction phase that brings all these designs into life.

Construction branch also has its own design items, such as the temporary structures to make the construction possible, including scaffold, formwork and any other work that is needed to facilitate the work.

Construction is a very complex phenomenon with lots of real life variables that cannot be easily controlled, as opposed to manufacturing something in a controlled factory environment or designing things on computer. To build what is shown in the designs and specifications in real life opens the door to failures at every small step of the way. Therefore, highly organized, standardized processes are needed to prevent or minimize failures. Because of this reason, construction and project management always go hand in hand.

Construction phase is at least as critical as the design as far as preventing failures. A construction phase failure can either negatively affect the construction phase itself, or if unidentified during construction, it will negatively affect the performance of the structure during its service life. You can read about construction failures in their respective categories linked above.

Final note:

Understanding failures in civil engineering and construction is the first and most critical step towards a good design and successfully executed construction. There are literally thousands of reasons and ways that structures can experience failure. Proper quality control measures and established standardized procedures are needed in every step of the way, during both design and construction.
And… as far as the featured image of this post in front page of our site, the Pisa tower in Italy… it is one of the most famous examples of “failure” in civil engineering, but it is so famous that, with its tilted appearance, it attracts tourists from all around the world. So it is hard to classify this as a failure for all practical purposes now, but a great success. The engineers now work to keep the tower this way.

By: A. Tuter

ConstructMagazine.Com

Reference:“How to Construct: Introduction to Civil Engineering, Structures and Construction” – A. Tuter, August 2024

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