The Earthquake Engineering Online Archive

Seismic behavior of tall liquid storage tanks

Niwa, Akira

UCB/EERC-78/04, Earthquake Engineering Research Center, University of California, Berkeley, 1978-02, 330 pages (540/N58/1978)

This report discusses the results of an experimental program in which a scaled model of a ground-supported, thin-shell, cylindrical liquid storage tank with a height greater than the radius was subjected to simulated earthquake excitation. Analytical investigations of out-of-round shell deformation of cylindrical tanks are also discussed. This experimental program was the second phase of a research project in which various scaled tank models were tested to assess the applicability of current seismic design practice to ground-supported, thin-shell, cylindrical liquid storage tanks. The first phase of the research considered "broad" tanks. The methods, model, and facilities used in the experimental evaluation of the seismic behavior of tall tanks are described. The principal results of this experimental investigation are presented in the form of a critical evaluation of current seismic design practice. It is observed that a significant out-of-round deformation response is induced in addition to a cantilever beam-type response, while typical design procedures assume the critical seismic response mechanism in ground-supported tanks is a quasi-static overturning effect, without distortion of the circular cross section. The development of an analytical procedure illustrating a possible correlative mechanism between the initial geometric eccentricity in the cross section of the tank model and the out-of-round shell deformation is described in detail. The results demonstrate that one of the most important causative mechanisms of out-of-round deformation response of the cylindrical tank is related to dynamic variations of the membrane hoop force developed in the shell circumference.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-78-04.pdf (13 MB)