Constructed
in 1939, Claytor Dam is a concrete gravity structure 1,142 feet
long with a maximum height of 145 feet. It consists of 10 non-overflow,
4 intake, and 10 spillway monoliths. The spillway section is 539.5
feet long and is controlled by nine vertical lift slide gates.
The gates are lifted and closed by a hoist above each gate supported
by reinforced concrete towers and a steel service bridge.
Previous
linear-elastic analyses had concluded that the reinforced concrete
towers would fail under the MCE event and could destroy some or
all of the gates. Quest Structures was commissioned to undertake
a new study to confirm these findings and if necessary to develop
remediation concepts to eliminate failure that could result in
uncontrolled release of water. The evaluation required identification
of potential modes of failure and assessment of sliding and rotational
stability of the strucutre in its damged condition.
Quest
Structures performed three-dimensional linear and nonlinear time-history
analyses of the spilway section consisiting of the spillway monoliths,
spillway piers, reinforced concrete towers, as well as the steel
service bridge. The dam structure was analyzed for the static
plus seismic loading. Potential modes of failure were identified
and the extent of tensile cracking, sliding dispalcment, and rocking
response were assessed using nonlienar time-history analyses.
The study also required assessment of structural stability of
all water-retaining sections of the dam. This was assessed by
2D nonlienar finite-element analysis of various sections including
the effects of tensile cracking and uplift pressure.
