Nonlinear Traveling-Wave Effects on Cooling Tower

The dynamic response of a tall reinforced-concrete hyperbolic cooling tower which has been designed for vertically incident seismic waves, based on a linear analysis, is examined for horizontally propagating waves of the same amplitude. The nonlinear response is also calculated, taking the material law of the reinforcing steel and of the concrete in the columns as well as lift-off and slipping of the separate foundations into account. The global response is increased for retrograde waves and decreased for prograde waves. It is decreased in a nonlinear analysis for both types of waves. The local response is increased for retrograde and prograde waves and is in all cases larger in a nonlinear analysis than in the corresponding linear one. When checking the seismic response of the retrograde wave in a nonlinear analysis with the design determined for vertical incidence, the following applies: The foundations have to be strengthened, the reinforcement of the columns is unaffected, but its area would possibly have to be increased, and the reinforcement in the lower part of the shell is sufficient.