Failure analysis and curvature-based failure criterion of super large cooling tower under strong equivalent static wind load

Abstract

More and more super large cooling towers are used in recent years. However, investigations on them under strong wind are still insufficient and there is still not an agreement failure criterion. In this paper, we conducted the failure analysis of a super large cooling tower with 253 m height under the equivalent static wind load. The finite element analysis procedure incorporates the multi-layered shell element, the softened damage model of concrete and the two-level secant algorithm in one framework. The numerical results show that the nonlinear response of the tower can be divided into four stages, i.e., the initial linear stage, the nonlinear stage, the softening linear stage and the failure stage. The failure of the cooling tower is caused by the loss of material strengths, i.e., the cracking of the concrete and the following yield of the meridian rebar. Finally, a curvature-based failure criterion is proposed to evaluate the failure of the cooling tower, in which the structure fails when the global curvature variation ratio ϰ reaches some definite values. ϰ is defined as the ratio of the total curvature variation with the initial total curvature of the cooling tower geometry. It can evaluate the total curvature variation in a global view. It is recommended that ϰ can be used as an index in the design of the cooling tower, and 1.0% and 3.5% can be deemed as the nonlinear and failure index, respectively.