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Construction and Equipment Spotlight
April 24, 1997

Why do some structures fall down?

Here's a few of the main reasons strucures can prematurely fail:

  • Site selection and site development errors: Failures often result from unwise land use or site selection decisions. Certain sites are more vulnerable to failure. The most obvious examples are sites located in regions of significant seismic activity, in coastal regions, or in flood plains. Other sites pose problems related to specific soil conditions such as expansive soils or permafrost in cold regions.

    Recognition of the characteristics of particular site conditions, through appropriate geotechnical studies, can lead to decisions about site selection and site development that reduce the risk of failure. Unnecessary exposure to natural hazards is an unfortunate consequence of historic patterns of human settlement.

  • Programming deficiencies: Failure can be defined as an unacceptable difference between expected and observed performance. The expectations of the client must be clearly understood by the designer and they must be realistic. When the project does not perform as expected, even if the expectations are unrealistic or unachievable within given economic restraints, the client is likely to define the project as a failure.

    A considerable volume of construction litigation results from unclear or unrealistic expectations. This type of "failure" can be avoided through communication during the programming phase of a project. A program should clearly define the scope and intent of a project at the outset, so that general agreement can be reached on evaluating the success of the completed project.

  • Design errors: These failures include errors in concept; lack of structural redundancy; failure to consider a load or combination of loads; deficient connection details; calculation errors; misuse of computer software; detailing problems including selection of incompatible materials or assemblies which are not constructable; failure to consider maintenance requirements and durability; inadequate or inconsistent specifications for materials or expected quality of work; and unclear communication of design intent.

  • Construction errors: Such errors may involve excavation and equipment accidents; improper sequencing; inadequate temporary support; excessive construction loads; premature removal of shoring or formwork; and non-conformance to design intent.

  • Material deficiencies: While it is true that most problems with materials are the result of human errors involving a lack of understanding about materials or the juxtaposition of incompatible materials, there are failures that can be attributed to unforeseeable inconsistencies in materials.

    Designers have come to rely on modern structural materials. However, manufacturing or fabrication defects may exist in the most reliable structural materials, such as standard structural steel sections or centrally-mixed concrete. Stone facade panels or glass curtain-wall units may contain undetected critical flaws. While these examples may in fact derive from human errors, they can hardly be considered design or construction errors.

  • Operational errors. Failures can occur after occupancy of a facility as the result of owner/operator errors. These may include alterations made to the structure, change in use, negligent overloading and inadequate maintenance.

    Not all maintenance-related failures are the fault of the owners and operators of facilities, however. Designers and constructors share the responsibility for durability of constructed projects, through appropriate selection of materials, detailing for ease of maintenance and quality of construction.

From "Construction Failure" (2nd edition) by J. Feld (deceased) and K. Carper, published in 1997 by John Wiley & Sons, Inc., New York.

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