STUDY ON FAILURE OF RC COOLING TOWER UNDER FLUCTUATING WIND LOADing CONSIDERING THE MATERIAL NONLINEARITY

To investigate the ultimate wind load and wind-induced failure process of cooling towers under fluctuating wind loading, a representative hyperbolic cooling tower was taken as an example and calculated in ABAQUS. The tower shell was modelled by a layered shell element, and the damaged plasticity model and a bilinear model were employed to represent the nonlinear behavior of concrete and reinforcement respectively. Based on ultimate static wind load analysis and on the comparison between the existed results attained from a smeared crack model, the incremental dynamic analysis (IDA) was conducted using the fluctuating wind load obtained from wind tunnel experiment. The failure process was illustrated from the deformation modes, from the displacement curves in IDA, from the crack distributions, from the stresses developments and, from the evolution of material plasticity and of structural stiffness. It was shown that the failure process and mechanism are identical for the damaged plasticity model and smeared crack model, but the former gave a little higher ultimate wind load and a much higher ductility. The difference between the results attained from static and dynamic calculations lies in the constitutive models, load distribution and dynamic effects. The failure of the structure under fluctuating wind load is also due to the concrete cracking and reinforcement yielding in the windward tower, where the meridian tension is predominant. However, 63.13% elements of the shell have cracked when the tower fails under the fluctuating wind load (V₀=57 m/s), this ratio is much higher than that under the static wind load. Thusly, future attentions should be paid on the stiffness deterioration due to the large-scale cracking in the shell under fluctuating wind loading.