Evaluation of the nonlinear seismic response of intake and control towers with the capacity spectrum method

The intake and control towers are tall hollow reinforced-concrete structures used for water discharge in earth dams. Its survival during earthquakes is crucial to permit the controlled water discharge in case of dam failure. This thesis examines the application of a static nonlinear procedure, the Capacity Spectrum method (CSM), to evaluate their structural integrity under strong earthquakes. The water outside and inside an intake tower is accounted for by added hydrodynamic masses. Three variants of the CSM are applied: a multimodal pushover, an adaptive version, and a combination of both. The accuracy of CSM analyses is assessed with time history analyses performed using commercial and in-house programs. The control towers are partially embedded in the soil of the dam and thus the soil-structure interaction must be considered. The nonlinear p-y curves used for pile analysis are adopted and implemented in the CSM. Two typical towers are used as case studies.