Indo-U.S. Forensic Practices: Investigation Techniques and Technology

Over the past three decades, the Technical Council on Forensic Engineering (TCFE) of the American Society of Civil Engineers (ASCE) has worked hard to establish and promote forensic engineering as a respected profession. The ultimate goal of forensic engineering is to improve quality and safety of constructed facilities. This paper reviews the development of TCFE in the US with particular emphasis on educational activities. Considerable work has been done in the area of integrating failure case studies and forensics into graduate and undergraduate engineering education. In addition, international developments in forensic engineering are discussed. Many of the recent efforts of the TCFE been focused on outreach to other countries. The differing legal, educational, and professional licensure practices in other countries make these outreach efforts interesting and challenging.

Machine foundations are dynamically loaded structures whose response depends on a number of parameters such as strength, stiffness, mass, damping, soil-structure interaction and fatigue. Performance based designs and evaluation procedures are gaining popularity particularly with respect to structures that have been built using codal provisions existing a few decades back. Enhancement of knowledge has led to various changes. But, machine foundations that have been designed and constructed in the past are seldom checked for their suitability using the present day knowledge. Some parameters that have been omitted or inadequately considered lead to malfunctioning of machine foundations. A four stage forensic engineering procedure is proposed for rehabilitation of these foundations. The stages involved are discussed taking three case study examples handled by the authors. It is felt extremely important that such investigations are documented and discussed by experts is engineering profession so that they can be used widely by practicing engineers.

In a recent and unusual occurrence, localized wind in the form of a cyclone with eye of the storm centered around NITT campus, caused considerable damage to many small and medium industrial units. Present paper gives details of investigations carried out to assess the mode and causes of failure. Personal visits, photographs and discussions with local citizens form the data for the study. After classifying the damaged structures into small and medium units, component level investigations based on failed portions were carried out. The details reveal possible causes of failure and methods to prevent such occurrences in future.

Geotechnical forensic engineering evolved from several famous failures which includes the leaning tower of Pisa and Transcona Fargo grain elevators. Geotechnical investigation starts at laboratory studies and ends in establishment of correlations to failure theories. This paper briefly describes the general forensic engineering practices and the state of practice in the US. Advanced geophysical testing methods including stress wave (Spectral Analysis of Surface Waves) and non-stress wave (Ground Penetrating Radar) techniques are also briefly described to demonstrate the potential of geophysics in forensic investigations.

The Geotechnical investigation is the backbone of any civil construction activity. The index and engineering properties of soil layers are to be estimated in a realistic manner for the design of structures. In general, the properties of soil vary randomly both in vertical and horizontal directions. The concept of probable soil description, effectiveness of exploration, factors to be considered in the report documentation of Geotechnical investigations are highlighted in this paper. The concept of Forensic Geotechnical Engineering (FGE) is also introduced. It is concluded that Geotechnical investigation is an Engineering ART and is to be done only by the qualified Geotechnical Engineer. Biased and unbiased properties along the borehole are to be reported for the proposed project site. Geotechnical report is to be prepared without using any JARGONS and can be followed by a non-technical person in the event of legal complications.

Reasons for including failure case studies within the undergraduate engineering curriculum have been made by various authors. Typically, specific cases have been integrated into the syllabi of engineering mechanics, structural analysis, and structural design courses. The case studies used generally include catastrophic structural failures, where failure can be defined as a structural collapse, often with significant loss of life. Many civil engineering undergraduate programs include a course in construction planning and management. The American Society of Civil Engineers (ASCE) Civil Engineering Body of Knowledge (BOK) for the 21th Century, Second Edition emphasizes a need for Civil Engineers to understand not only the technical areas of analysis and design, but also more of the project management issues that enable a project to go from design to fruition. Hence, it is likely that more programs will include construction management courses. This paper deals with the integration of failure case studies into a construction management course. In addition to structural failures, this course looks at the definition of "failure" from an engineering/construction perspective. It explains that failure includes the inability of an engineered facility to perform as designed. It further explains how failure to be constructed within reasonable time and budgetary constraints falls within the definition of failure. While most students may have the pre-conceived notion that failures are only caused by design deficiencies and perhaps natural hazards, the examples used in this course emphasize how many failures are caused by deficiencies in the design and/or construction process itself. In addition to the use of more typical and catastrophic failure case studies, such as the Hyatt Regency Walkway Collapse (Kansas City, Missouri), and the L'Ambiance Plaza Collapse (Bridgeport, Connecticut), the course makes extensive use of the Montreal Olympic Facility design and construction to demonstrate how deficiencies in the design and construction process can lead to extreme constructability problems and exorbitant cost overruns. The author also shows how the inclusion of the case studies addresses some of the more difficult areas to address in the Accreditation Board for Engineering and Technology (ABET) evaluation criteria, such as the understanding of the impact of civil and environmental engineering solutions in a global and social context.

Wood has performed remarkably well as a construction material in a variety of structures for millennia. Occasionally, problems occur that require investigation to understand the nature and cause of the problem. With wood, not all forensic investigations are the result of catastrophic failure, but, more often than not, are related to performance-based issues. Very few catastrophic failures of wood structures resulting in significant financial loss or loss of life have occurred, although it happens. For example, in 1773 the collapse of a timber-frame in a meetinghouse resulted in five deaths and 48 injured. The incident was recorded in detail at the time and may very well be the first forensic investigation of a wood structure in the United States (Clark, 1998). The collapse of the Texas A&M bonfire in 1999 was not a typical structure, but resulted in the death of 12 students (U.S. Fire Administration, 1999). Investigation of this wood structure was very complex and involved numerous professions. Similarly, torrential rains caused the collapse of a three-story building in Mumbai in 2005, which resulted in the death of six people (The Hindu, 2005). Most forensic investigations involving wood may be less noteworthy than these, but all should follow the same investigative process as that for any catastrophic or performance failures. The investigative process is described by the American Society of Civil Engineers (ASCE, 1989). Additional resources that describe the forensic process or provide case studies include Nicastro (1997), Carper (2001) and Ratay (2000). While not necessarily intended as forensic engineering references, there are numerous sources of information that can help explain why a failure occurred, such as Perrow (1999) and McDonald (2003). The purpose of this chapter is to identify key steps in the investigative process of forensic engineering and emphasize aspects that should be considered for wood structures.

The paper proposes a first stage structural health monitoring methodology using natural frequencies and static deflections as damage indicators. The idea is that the first stage monitoring can be done for a large number of bridges and vulnerable structures in a remote manner and the features extracted from the data should help in determining whether any second stage detailed investigation is warranted. Hence, simple, fast and robust strategies are required for estimating the health of the structure using some of the globally available response data. Identification methodology developed in this paper is applicable to distributed smeared damage, which is typical of reinforced concrete structures. Simplified expressions and methodologies are proposed and validated in the paper, numerically and experimentally towards damage estimation.

Investigations of claimed structural failures often lead to conclusions based on structural factors including strength and serviceability. Typically, these conclusions are absolute since they result from objective comparisons of results to limits prescribed by owners and/or governing agencies. Occasionally, however, the failure of a structure may be defined by human factors, which are more subjective. A case is presented herein (Kellogg 1988) that describes the evolution of an investigation from one of only structural factors to one that included human factors. Discussion focuses on "failure" being defined by the inability of the structure to restrict human annoyance. In this case, excessive building vibrations were claimed to render the occupants unable to perform their work as intended. Investigation, presentation, and solution processes are described in order to contrast differences between absolute failure decisions based on structural factors and relative failure decisions based on human factors.

Building codes have been the primary source for guidance in the design and construction of building structures for many decades. The use and application of building codes has been instrumental in safeguarding the health, safety, and welfare of the people. In this context, India has not been an exception. The publication of the first edition of the National Building Code of India (NBCI) in 1970 was a result of exhaustive research into the issues that most affect the Indian built landscape: lack of uniformity of the diverse regional policies, the need for development of a sound and updated building construction program in which 50% comprised new housing, and the need for developing new materials and construction techniques. Two major revisions were made that reflect the current state of building construction triggered by technological changes, increases in the population, and the concern for public safety, thus resulting in the current, 2005 edition. Likewise, the International Building Code (IBC), first published in the United States in 2000, also addresses similar concerns, making these two documents essential design and construction references in their respective countries. A sound knowledge and proper application of the building design and construction provisions in building codes and standards is essential while performing a forensic investigation. This paper reviews the organizational structure of both codes, and will present a comparative example using the Structural Design Provisions of both codes.

Structural monitoring is used as a diagnostic tool for detecting or inferring the presence of defects/damages and for scheduling maintenance operations. It has become important to determine the safety of the critical structures by the Non-Destructive Testing (NDT) for evaluation of their strength and integrity. This assessment is essential for the repair, retrofit, rehabilitation, life extension, or replacement of the structure in question. Fiber optic sensors are attractive sensing devices as an NDT tool; given their small size, light weight, and dielectric glass construction that renders them immune to electrical noise and electro magnetic interference. Optical fibers offer the possibility to be embedded within cement or concrete without affecting their performance and used as sensitive, but rugged, transducers of mechanical perturbations. Fiber optic sensors have the capability to be embedded prior to curing, into the concrete structural elements for non-destructive evaluation of structural integrity and the measurement of the internal state of stress. Sensors can also be surface mounted on concrete or steel members. There are challenging problems and issues while applying fiber optic sensing technology for monitoring of concrete structures. Systematic studies on the new sensors have been carried out in the laboratory to solve the following issues/problems: 1. Safe embedment of fiber optic sensors in concrete structures 2. Elimination of errors due to temperature induced apparent strain 3. Assessment of performance of the sensors under static and cyclic loading 4. Assessment of the long term stability of the fiber optic sensors In this paper, the potential of fiber optic sensors for monitoring concrete structures has been highlighted. Details of the laboratory studies carried out in solving some of the technical challenges and issues for implementing the fiber optic sensing technology to the field problems are also covered.

Data in forensic engineering come from different sources based on site visits, photographs, texts and videos. The way the data had been obtained and the background knowledge of the person who generated the data all play an important role in further investigations. In this study, visual and oral information provided for certain failures are used as basis to generate a model for analysis and interpretation to diagnose the possible mode of failure. Fuzzy analysis and finite elements are used in the analysis. The information may contain uncertainty aspects which are also covered using statistical means.

Commercial Remote Sensing and Spatial Information (CRS-SI) technologies, due to their natural geospatial representation and unique data acquisition, offer great potentials in forensic investigation applications. However, limitations in viewpoints and reliance of user experiences may force the court of law to limit the use of CRS data as direct evidences. This paper discussed the forensic applications of satellite/airborne and ground-based remote sensing techniques and their resolution requirements. In particular, close-range, airborne photogrammetry and terrestrial LiDAR scanning are discussed in greater details. Structural damage detection from recent Haiti earthquake is used to demonstrate that extensive experiences and a priori information are necessary when data resolution is not sufficient.