Ever more structural failures make the news; their investigation has become an active and lucrative field of professional practice in which expert consultants/witnesses are retained to investigate the causes of failures, as well as to provide technical assistance to the parties and their attorneys in the litigation of the resulting claims. Since nearly all structural deficiencies and failures create claims of damages, disputes and legal entanglements, forensic engineers operate in an adversarial environment; hence, in addition to their technical expertise, forensic engineers need to have at least some familiarity with the relevant legal processes and need to know how to work effectively with attorneys.
Figure 1: Heavy cracking developed in large industrial reinforced concrete floor slab generating a multi-million dollar claim.
Causes of Failure
Structural failure does not have to be a "catastrophic collapse"; it may be a "nonconformity with design expectations" or a "deficient performance." Collapse is usually attributed to inadequate strength and/or stability, while deficient performance, or so-called serviceability problems, are usually the result of abnormal deterioration, excessive deformation, and signs of distress. In short, failure may be characterized as the unacceptable difference between intended and actual performance.
What can go wrong in the design-construction process and in the use of a structure that may result in immediate or eventual failure? A lot!
Negligence: failure to properly analyze or detail the design, or disregard codes and standards.
Incompetence: failure to understand engineering principles or respect the technical limitations of materials or systems.
Ignorance, oversight: failure to follow design documents and safe construction practices.
Greed: Short-cuts; intentional disregard of industry requirements and safe practices.
Disorganization: failure to establish a clear organization and define roles and responsibilities of parties.
Miscommunication: failure to establish and maintain lines of communication between parties.
Misuse, abuse, neglect: using the facility for purposes beyond its design intent or foregoing preventive maintenance.
Any one of these can be the underlying reason for an eventual failure of the structure and the resulting claims/disputes/litigations.
All of the parties on a construction project have legal responsibilities as defined by their contracts, and by state and federal laws. But professionals performing "value engineering" and "peer reviews" generally do not have liability for the safety of the constructed facility.
Figure 2: Forensic investigation exposed both design and construction defects.
Codes, Standards, Regulations
In forensic engineering practice, design codes and standards provide the baseline for the design requirements that were in effect at the time when the design was done, and define the minimum level of performance that the failed structure should have met. Satisfying the governing Code is a minimum requirement. Copies, especially old copies, of design codes, standards and manuals are important references on a forensic engineer’s bookshelf.
During construction, OSHA inspectors make unannounced visits to construction sites, issue violations when warranted, and impose fines for violations. By act of Congress, OSHA investigates all construction failures where fatalities occur. An OSHA report opines on the innocence or culpability of the contractor(s) at the site; it does not address designer’s responsibilities. OSHA regulations and OSHA reports are significant documents for the forensic engineer to deal with in his/her engineering investigations and in the assignment of responsibilities.
Figure 3: The entire floor had to be removed.
Standard of Care, and Duty to Perform
It is most important that the forensic engineer understand the accepted standards that structural designers and contractors have to meet.
Structural design engineers are retained to provide a service to: (1) examine existing conditions, (2) develop solutions to meet specified goals, satisfy industry requirements, and serve stated purposes, and (3) prepare drawings and specifications to show what is to be constructed.
The undertaking of a design project by an engineer implies that he/she possesses skill and ability sufficient to enable him/her to perform the required services at least ordinarily and reasonably well, and that he/she will exercise and apply to the project his/her skill, ability and judgment reasonably and without neglect.
Since the engineer, when providing professional services, is exercising judgment gained from experience and learning, and usually provides those services in situations where certain unknown or uncontrollable factors are common, some level of error in those services should be acceptable.
There are legal definitions arising from Bench Approved Jury Instructions [see Reference 5] and other definitions created by attorneys and engineers. The substance of all of them is reflected in the author’s simplified working definition of the Standard of Care, which is as follows: "That level and quality of service ordinarily provided by other normally competent practitioners of good standing in that field, when providing similar services with reasonable diligence and best judgment in the same locality at the same time and under similar circumstances."
The fact that an engineer makes a mistake is not sufficient to lead to professional liability on the part of the engineer, even if that mistake is the cause of damage or injury. In order for there to be professional liability, it must be proven that the services were professionally negligent, i.e., that they fell beneath the Standard of Care of the profession.
In the United States, the court requires that qualified experts testify to the Standard of Care that is applicable to the case on trial and testify to the professional’s performance as measured by that standard of care.
The principle of Standard of Care does not apply to constructors, since they are not "professionals" in the sense of making independent evaluations and judgments based on learning and skill. They are held to a Duty to Perform, i.e., to follow strictly the plans and specifications and the provisions of their contracts.
Figure 4: The slab was redesigned.
Reasonable Degree of Engineering Certainty
Professional opinion cannot always, and does not have to, be with one-hundred percent certainty. The courts require that the opinion be only "with reasonable degree of engineering certainty." The phrase "reasonable degree of scientific certainty" arises from courtroom rules of evidence and, as such, is a legal term. [see Reference 2]
Engineers should be thorough in their investigations and careful with the statements of their opinions. They should be aware that forensic investigation, advice to a client, and expert testimony can be subject to claims of negligence, and the liability may extend far beyond the fee for services.
Figure 5: The entire slab was rebuilt. The multi-million dollar claim was settled after several days of diligent mediation.
Types of Cases and Scopes of Work
According to when the forensic expert consultant is engaged, the types of cases can be categorized in three groups:
- When a "condition" surfaced
- When a collapse occurred
- When litigation is already in progress
In these cases, typical scopes of work, hence the activities of the expert consultant, would include the following:
When a "Condition" Surfaced
Depending on the client’s requirement, and/or the severity of the situation, the scope of work may be one of the following (in the order of increasing effort):
- Simple visual (due-diligence) inspection, oral or written letter-report of observations only
- Inspection, quick-and-tentative opinion, report
- Inspection, some analysis, opinion, report
- Inspection, probing and testing, analyses, opinion, report
- Inspection, probing and testing, document reviews, analyses, report
When a Collapse Occurred
And the consultant is engaged immediately after:
- First-response and preliminary assessment
- Development of investigation strategy
- Fact-gathering and document review
- Probing and testing
- Engineering analyses to determine cause(s) and responsibilities
- Litigation support (see "When litigation is already in progress")
When Litigation is Already in Progress
When the consultant is engaged some (usually much) time after the failure:
- Cataloging and review of documents
- Engineering analyses
- Review of other experts’ reports
- Review of deposition transcripts
- Writing of report
- Meetings with attorney/client
- Writing affidavit
- Assisting attorney with expert disclosure
- Assisting attorney with questions for depositions of others
- Preparing for and giving own deposition
- Preparing for and participating in dispute resolution
- Assisting attorney in preparation for trial
- Giving expert testimony at trial
The extent to which these items are performed depend on the nature and magnitude of the failure, fatalities, if any, the dollar amount of damages and claims, and often on the experts and attorneys involved.
Failures almost always result in repair or in demolition and reconstruction (see Figures 1 through 5 as an example). Some forensic investigators do not get involved in the post-investigation design and construction work because they, or their clients, feel that the credibility and objectivity of their opinions and recommendations may be questioned on the grounds that they are looking to profit from those recommendations.
The Process of Technical Investigation
The process of determining the cause(s) of a failure depends on many factors, including the elapsed time between the failure and when the investigator begins his/her work; the nature and magnitude of the failure; the number and types of injuries and fatalities, if any; the dollar value of damages, repairs and claims; the availability of design and construction documents; the available evidence; and often on the experts, attorneys and insurers involved. (Discussion of the process is not included in this article; the reader is directed to Chapter 6 of Reference 1 and Chapter 3 of Reference 2. )
In general, one should list all possible causes, no matter how far-fetched, then first eliminate those that are obviously not realistic possibilities (be careful with "obviously"), and then eliminate those that do not satisfy the evidence and do not stand up to logical engineering examination. Hopefully one will arrive at one cause with reasonable certainty. [With tongue-in-cheek the writer suggests the Martini Analogy where, starting with a full glass of the cocktail and after deliberately sipping it, one ends up with the olive in the bottom (Figure 6).] It may be that more than one cause remains as a possibility. Often, different investigators arrive at different causes. The latter is not infrequent, because two engineers working independently of each other may have access to different data, may approach the problem from different directions, may put unequal emphases on the same evidence, and perhaps - last but not least - because, knowingly or unknowingly, they are influenced by their preexisting opinions and biases.
Figure 6: The Martini Analogy.
In the U.S., damage disputes are resolved in one of several ways, of which the following appear to be common:
- Settlement discussion - among the parties, usually involving compromise by all.
- Mediation (usually non-binding) - with an impartial mediator, agreed upon by the feuding parties, seeking to bring about a resolution through diplomacy and conciliation.
- Arbitration (binding or non-binding) - with one or more arbitrators hearing arguments of the parties, taking testimony and evidence, asking probing questions, and deciding on a resolution through a quasi-judicial process.
- Trial in court - before a judge and usually a six-member jury resulting in a binding verdict.
Settlement discussions are the best, least bruising, most private, and least expensive ways of resolving disputes. Mediations tend to bring out all, or nearly all, the facts and are successful and satisfying in their outcome if the parties act in good faith. Arbitration has the attraction of speedy outcome, relative privacy of the parties, and less cost than a trial. Only a handful of cases of structural failures end up in trial in court in the United States. The feuding parties usually try to avoid a trial in court for various reasons that include its lengthy procedures, great expense, and often unpredictable outcome.
Expert consultants are usually not present at settlement discussions, although the parties may rely on their respective expert consultants in formulating their positions. Expert consultants usually do participate in mediations, indeed, they are often the primary presenters of their clients’ technical positions and provide continuing input throughout the ongoing arguments. Arbitration seldom proceeds without expert witnesses, in part because the arbitrators often probe into deeply technical matters of the case and, in part, because the parties want credible and authoritative presentations of their technical positions. The testimony of experts at a trial of a case involving engineering and construction is normally required by the court for the purpose of clarifying to the trier of fact (the judge or the jury) the technical aspects of the case. Also, the feuding parties want the trier of fact to hear their own technical positions expressed by their own experts, as well as to hear their challenges to the opposing experts’ opinions.
Individual versus Group Practice
While most of the forensic structural engineering work is performed by engineering firms of various sizes, a fair amount is performed by individual practitioners. Engineering firms in established design practices may suddenly find themselves in, or intentionally "moved into", the area of forensic investigation. Individuals with long-time design and construction experience are likely to "hang out the shingle" and step into the practice; university professors make themselves available when the opportunity arises.
An engineer should seriously consider all of the pros and cons before deciding to enter into private practice. It is challenging, satisfying and lucrative work, but the world of adversity is not always pleasant. A client in need of expert engineering advice and litigation support should weigh all the pros and cons in light of the manpower needed for the project; decide whether his/her need is for only one particular specialty or for a range of expertise; and, consider the level of trust and comfort with the individual(s) who will be doing the actual technical work, writing the report(s), giving depositions, participating in dispute resolutions and testifying in court in the client’s behalf.▪
This article relies heavily on References 1, 2 and 3; and is, in part, modified and condensed from the author’s lengthier treatise, "Forensic Structural Engineering - Focus on the United States", in the May 2007 issue of Structural Engineering International, IABSE.
 RATAY, R.T., Ed., Forensic Structural Engineering Handbook, McGraw-Hill, Inc., New York, 2000.
 LEWIS, G.R., Ed., Guidelines for Forensic Engineering Practice, ASCE, Reston, VA, 2003
 RATAY, R.T., Ed., Structural Condition Assessment, John Wiley & Son, Inc., Hoboken, NJ, 2005
 RATAY, R.T., "Forensic Structural Engineering - Focus on the United States", Structural Engineering International, May 2007, IABSE, Zurich, Switzerland
 BAJI 6.37, Duty of a Professional, California Jury Instructions, Civil, West Publishing Company, January, 1986