Structural Failures

Since man first began to build, there have been times when our buildings have not met expectations. Common problems include leaks, unsightly cracks or sagging, and in rare instances, total collapse. Modern building codes have greatly reduced, but cannot totally eliminate, the risk of being hurt or killed in a structural collapse. For instance, the risk of death in a car accident (per hour of exposure) is about 35,000 times higher than from a structural failure. But while the probability of structural failure is low, the consequences can be tragic, and engineers continually seek understanding of why buildings fail, who (if anybody) is at fault, how best to repair the damage, and how to prevent similar failures.

For more than a quarter century, Exponent’s structural engineers have been applying these principles at sites of the most notorious structural catastrophes, such as the Oklahoma City bombing, the World Trade Center, and the Kansas City Hyatt Regency collapse. Often these investigations are multi-disciplinary, at times involving engineers specializing in geotechnical, mechanical, and material science. Exponent has investigated countless failures in a broad range of structures, including buildings, industrial structures, transmission towers, telecommunication towers, tunnels, cranes, and bridges. We recognize that discovering the true cause of a failure is of no value unless we can effectively convey technical engineering aspects, particularly to an audience whose expertise lies elsewhere.

Investigation of structural failures follows the classic scientific method:

  1. Observation of the evidence, which often includes careful photographic documentation, measurements, and field notes. It also includes witness interviews and review of information about the accident site (i.e., construction drawings, building-department files, geotechnical reports). 
  2. Hypotheses about the failure mechanism are drawn based on the observations. Often, there are multiple competing hypotheses regarding the failure mechanisms and associated contributing factors. 
  3. The hypotheses are tested. In addition to the observations made in Step 1, each hypothesis is subjected to the laws of physics in the form of engineering calculations, material science, and perhaps laboratory testing. 

Application of the process leaves the investigating engineer with one or more plausible hypotheses, typically with enough information to determine which (or which combination) is most likely. Understanding the root cause of the failure enables the full extent and severity of the damage to be assessed and repair options evaluated.


Our services include:

  • Quick response to failures to assist with stabilization of the debris, preservation of important evidence, and working with oversight agencies such as OSHA or local jurisdictions.
  • Comprehensive failure investigation, including determination of cause(s), assessing the nature and extent of the damage, and development of repair options
  • Failure reconstruction using advanced structural analysis, often incorporating computer simulation to recreate the precise failure mechanism.
  • State-of-the-art computer visualization and animation tools to reconstruct and illustrate key aspects of the failure in a memorable and understandable manner.