Located
on the Pigeon River in Haywood County, North Carolina, Walters
Dam is a variable-radius arch dam with a crest length of about
900 feet and a maximum height of 192 feet. Walters Dam was built
in 1929 as 13 independent cantilever monoliths, each 50 feet wide
and separated by construction joints 8-foot wide. After completion
of the cantilever monoliths, all construction joints were filled
by concrete. The Walters Dam spillway is located at the center
of the dam and is controlled by 14 tainter gates, each 24 feet
wide and 10 feet high.
As
a subcontract to ARCADIS Geraghty & Miller, Inc. of Chattanooga,
Tennessee, Quest Structures performed earthquake ground motion
studies and static and seismic safety evaluation for Walters Arch
Dam. This work was carried out as part of the Federal Energy Regulatory
Commission (FERC) five-year dam safety inspection report.
The
studies included estimates of the maximum earthquake ground motions,
development of acceleration time histories, and three-dimensional
static and dynamic analyses of the dam. Three-dimensional finite-element
models included the concrete arch dam, foundation rock, and the
impounded water. Various loading conditions up to and including
the PMF as well as the seismic loads were considered and analyzed.
Evaluation for the extreme loading combinations consisted of four
time-history dynamic analyses, each using a 3-component set of
acceleration time histories as the seismic input.
