Nonlinear analysis of a RC cooling tower with geometrical imperfections and a technological cut-out

Abstract

The analysis of nonlinear deformation and ultimate load should be a vital element of the checking-design of cooling towers. This issue is discussed in the paper with respect to an existing cooling tower with large geometrical imperfections and a cut-out made for gas discharge. A brief theoretical background is given, with special attention paid to the finite element model and constitutive relations for reinforced concrete. The numerical analysis deals with three cases: (1) perfect hyperboloid shell of revolution, (2) actual shell with measured geometrical imperfections of the shell mid-surface, (3) imperfect shell with a cut-out. Two types of nonlinearities are considered: (a) material nonlinearity only, (b) material and geometrical nonlinearities. The computations are carried out for a cooling tower shell pinned at the bottom contour. The dead load and wind pressure are applied to the shell. Finite element code A nka is used as the main tool for the numerical analysis. The results of computations for a perfect hyperboloid shell are compared with the results obtained using the DIANA package. It is noted that a considerably softer response corresponds to larger deformations and advanced cracking. The geometrical imperfections only slightly influence the response of the shell. The cut-out introduced into the imperfect shell does not significantly change the shell deformations either.