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COMMISSION INTERNATIONALE DES GRANDS BARRAGES ------- VINGT-SIXIÈME CONGRÈS DES GRANDS BARRAGES Autriche, juillet 2018 ------- HOW TO DEAL WITH AGING PRESTRESSED ANCHORS IN DAMS: A NORTH AMERICAN PERSPECTIVE * Donald A. Bruce1 and John S. Wolfhope2 1 President, GEOSYSTEMS, L.P. 2 Vice President, FREESE AND NICHOLS, INC. U.S.A. 1. INTRODUCTION Prestressed rock anchors have been installed in dams throughout the world since 1934. In the U.S., the first installation was in 1964. Since then, well over 400 case histories have been recorded by the authors [1] [2] [3]. Practice has evolved over the years, governed by, and reflected in, successive editions of the Post-Tensioning Institute’s “Recommendations” documents. Since 1996, virtually all projects have been completed using what may reliably be referred to as “Permanent” anchor systems (i.e., with PTI Class I Protection) and responsive drilling, water testing, and grouting methodologies. However, older-vintage anchorage systems did not generally include corrosion protection systems which would be acceptable today, and did not generally provide the means to measure residual load or the state of corrosion in-situ. This is a challenge facing dam owners throughout the world, since early anchor technology was largely driven by a limited number of European post-tensioning suppliers operating internationally. * COMMENT TRAITER LES ANCRAGES PRÉCONTRAINTES DE VIEILLISSEMENT DANS DES BARRAGES : UNE PERSPECTIVE NORD-AMÉRICAINE 702