With the development in Europe in the later 1800s of a rational method for evaluating structural stability combined with practical experience, U.S. engineers gained greater confidence in increasing the structural height and loadings on masonry dams, as they were known then. This lead to record setting heights in the U.S. for several gravity dams built for water supply purposes for major U.S. cities.
As records were being set, a few dramatic concrete gravity dam failures occurred which sparked wide debate concerning whether or not rational methods adequately accounted for various destabilizing external forces acting on a gravity dam. Many practicing engineers agreed that although estimates and likely ranges can be assigned to these forces, for some exact values are indeterminate. Recognition was also given to the variable nature of material strength properties. This lead to the adoption of the use of safety factors to better account for the indeterminate and variable nature of such factors.
Since many U.S. gravity dams in service today were constructed decades ago while design practices were still evolving, historical background for design and construction practices will be presented to provide today’s practitioners with a better understanding of potential vulnerabilities in these structures. Select noteworthy gravity dam failures will be presented as well with an emphasis on lessons learned from these failures.
Robert A. Kline, Jr., P.E.
Vice President, Gannett Fleming, Inc.
Bob is a Vice President of Gannett Fleming, Inc. and Manager in the firm’s Dams and Hydraulics Section at their Camp Hill, Pennsylvania headquarters office. Over the past 26 years, he has been continuously involved in the planning, design, and construction of over 85 existing rehabilitation and new dam projects. Bob specializes in concrete gravity dam design and was involved in the first roller-compacted concrete (RCC) gravity dams constructed in Pennsylvania, Maryland, and California. In 1998-2003, he served as the RCC Design Task Leader for the Olivenhain Dam in San Diego, California; at 318-feet, it is the tallest new concrete gravity dam constructed in North America in the past 40 years. Throughout his career, he has authored and co-authored numerous papers on the various aspects of concrete gravity dams. Bob is currently serving as a lead designer for several large dam rehabilitation projects in New York and Virginia.