Collapse Simulation and Response Assessment of a Large Cooling Tower Subjected to Strong Earthquake Ground Motions

摘要

Large cooling towers in thermal power plants and nuclear power plants are likely to suffer from strong earthquakes during service periods. The resulting destructions of the cooling towers would endanger the power plants and threaten the security of the related areas. It is important to use effective means to evaluate the safety status of the cooling towers and guide further precautions as well as retrofitting efforts. This paper is therefore focused on an elaborate numerical investigation to the earthquake-induced collapses of a large cooling tower structure. A complete numerical work for simulation of material failure, component fracture, structural buckling and system collapse is presented by integrating the stochastic damage constitutive model of concrete, refined structural element models, and some other key techniques. Numerical results indicate that the damage behavior and collapse mode of the cooling tower are affected notably by the randomness specification of ground motions. The collapse mechanisms of the cooling tower are studied from the energy absorption and dissipation points of view. An effective energy-based criterion is introduced to identify the collapse of the cooling tower under ground motion excitations. While distinct collapse modes are observed, the collapse criterion can predict well the damage and failure of the cooling tower. The proposed methodology is vital to better understanding the disastrous mechanisms and potential failure paths in optimal design of the cooling towers to ensure safety.