Collapse Mechanism and Failure Criterion of Superlarge Cooling Tower under Tornado

Abstract

In this study, the tallest cooling tower (228 m) completed construction in the world in northwest China was chosen to investigate wind-induced failure mechanism of superlarge cooling towers under tornado. A multiscale finite-element model of the structure was established based on the layered shell element method, and a wind tunnel pressure test was carried out using the tornado simulator. Wind pressure distribution characteristics on inner and outer surfaces of the cooling tower under tornado were analyzed. Moreover, characteristics of the whole wind-induced collapse process of the cooling tower under tornado were studied by combining incremental dynamic analytical method, and the collapse mechanism of a superlarge cooling tower under tornado was extracted. Finally, the failure criterion of the structure under tornado based on the variation rate of the torsion angle was proposed. Results demonstrated that wind pressure showed a circumferential even distribution pattern on the surface of the superlarge cooling tower under tornado, and it generally presented negative pressures. When the cooling tower is located at the tornado vortex core, it is the most dangerous and vulnerable to collapse. Under tornado effects, the cooling tower presented bypassing suction and torsional collapse attitudes from inside to outside. The cooling tower element is designed to improve the antitornado bearing capacity by developing a membrane mechanism. The cooling tower collapsed and failed when the torsion angle failure index φ>0.25.