Journal of Performance of Constructed Facilities

To properly maintain our public infrastructure, civil engineers must learn new methods of inspection technology. Current inspection techniques required for our nation's bridges as well as locks and dams primarily consist of visual and subjective observations. When these inspections indicate that a structural or functional problem may be developing, many times more sophisticated inspection technology may be required. Nondestructive (NDE) testing methods can provide an answer to further determine the extent of a structural or functional problem. This paper presents the abbreviated results of a detailed literature review to identify the most widely used NDE techniques applied to civil engineering structures. In addition, a short questionnaire was developed and sent to state highway organizations. The literature suggests that acoustic emission testing is widely used while the questionnaire revealed that ultrasonic testing is most popular among state highway agencies.

Partially or totally buried concrete hazardous-waste tanks pose a difficult problem when evaluation of their integrity and concrete quality is required. A visual survey is very limited, and destructive sampling is usually not practical because of poor access to the tank walls and the risk of spillage from the tank into the surrounding environment. This paper introduces several nondestructive testing (NDE) techniques to overcome the foregoing difficulties, including ultrasonic pulse velocity, impulse response, parallel seismic, and cross-hole sonic logging. These test methods are described, and their application is illustrated by case records from a tank evaluation program implemented at Los Alamos National Laboratory, New Mexico, to determine the residual life of 14 low-level nuclear waste tanks, most of which have been in service for more than 30 years.

This paper presents an analysis of damage factors for low-rise structures exposed to hurricane winds. The intent is to provide a systematic approach for estimating wind damage and loss for a population of structures over a wide range of conditions, by beginning with several logical hypotheses and developing these into expressions for damage. The resulting equations have been validated with limited data from Hurricanes Betsy and Andrew.

Heuristic construction knowledge generated while contracting is seldom recorded and transferred to other workers. Experiences of past mistakes as well as efficient work practices are crucial means for saving money, time, and improving the safety and quality of construction. With the rising costs of construction and the increased demand of time constraints on contractor schedules, few members of the construction industry can afford to waste time and resources on errors or ineffective work practices. The Constructability Lessons Learned Database (CLLD) prototype described in this paper is a leading edge method of automatically gathering, systematically organizing and efficiently applying vital construction information to a contractor's daily activities. This paper presents a review of previous and current attempts at database constructability programs, uses of constructability feedback systems, challenges to develop and utilize such systems, and an overview of the design and development of the CLLD prototype. The overview describes knowledge elicitation techniques used to gather constructability knowledge, the design of the system (organizing and classifying construction information for efficient retrieval and expansion), and system's implementation, validation, and operation. The conclusion discusses future extensions of the CLLD concept in the construction industry.

This paper examines the question of human error as a factor in structural failures. Even though increasingly sophisticated tools and methods are available, designs for structures must, necessarily, also be based on the analysis of errors or situations that have arisen in the past; although these past events might be considered “negative” experiences, they do have an important didactic function for future operations. In order to understand such past events, an interpretative reference model must be defined within which the fundamental distinctions and classifications can be organized. This poses many problems that may arise either from the researcher's ability to identify the primary and the secondary causes of a failure or from the type of approach adopted. This paper seeks to show how the interpretation of events may be influenced by different factors, i.e., the availability (or lack) of information, which constitutes a limitation, or the scientific validity of any analyses carried out, which may themselves be limited. Hence, interpretation will be affected by the deterministic level of research adopted by the researcher.

Diaphragm walls with thicknesses ranging from 600–1,200 mm are increasingly used as both temporary and permanent supports for excavations in congested urban areas. This paper describes the performance of two propped excavations supported by diaphragm walls in stiff residual soils in Singapore. Performance measures include lateral wall deflections and wall-bending moments reduced from wall-inclinometer readings. A method of back-analyzing bending moments in a diaphragm wall from measured wall-inclinometer data for an uncracked and a cracked wall section is also presented and discussed. The finite element method was used for back-analyzing the performance of the two case histories. A series of parametric studies were also performed to study the effects of wall stiffness, wall embedment depth, and prop stiffness on the performance of diaphragm walls for excavations in stiff residual soils. Back-analysis indicated that cracking was accompanied by a substantial reduction in the bending moment in the diaphragm wall and a small increase in the lateral wall deflection.