Investigations in conjunction with operating engineering works and structures are receiving increasing emphasis throughout North America. The most obvious reason for the investigations is observed distress of the works, while less obvious but common causes are decaying infrastructure, advances in state-of-the-art engineering, and increased regulatory activity due to safety concerns. These latter causes frequently lead to modification of the original design.
In the early 1980s, the need for maintenance and rehabilitation of the nation’s engineering-works infrastructure was recognized and widely published as a national problem of great magnitude. Phrases such as “decaying infrastructure” and “crumbling public facilities” were used by the engineering and construction industry publications or by the general news media. The Public Works Improvement Act (Public Law 98-501) constituted a significant step in formulating a national response to the long-term intrastructure needs of our modern society (ENR, 1985; Pender, 1985).
The relative cost of continuing operations, maintenance, and rehabilitation versus the investment in new construction is increasing. One indicator of the shift is seen in the civil works budget of the U.S. Army Corps of Engineers. In fiscal year 1967, construction and operations and maintenance accounted for 79 percent and 16 percent, respectively, of their budget. In fiscal year 1983, construction accounted for 42 percent and operations and maintenance for 40 percent. In fiscal year 1986, the construction budget was $0.8 billion, and the operations and maintenance budget was $1.4 billion!
Advances in state-of-the-art engineering have produced improvements in design criteria in such areas as earthquake engineering, maximum hydrologic events, strength and deformation properties of soil and rock materials, and methods of analyzing the response of structures to forces acting upon them.