ORIGINAL PAPER Effect of local geometrical imperfection on dynamic buckling of cylindrical storage tanks A. Chikhi 1 • M. Djermane 1 Received: 31 October 2017 / Accepted: 29 January 2018 Ó Springer International Publishing AG, part of Springer Nature 2018 Abstract Steel cylindrical tanks are the most susceptible to damage due to dynamic buckling during earthquakes. The production of cylindrical shell without imperfections is very difficult or sometime even impossible. The most previous research to study the geometrical imperfection in the shell of steel tanks using various methods did not deal with the fluid–structure interaction (FSI) and the dynamic loads. In this paper, the FSI numerical model is used to estimate the effect of local geometrical imperfection with dynamic buckling of fluid-filled tanks. The liquid inside the tank was modeled using specific Ansys’s finite elements and fluid–structure interaction. The calculation includes modal and time history analysis, including material and geometric nonlinearity. Then a typical cylindrical tank is analyzed by the application of three different stability criteria to estimate the critical PGA. The obtained dynamic buckling results of the perfect and imperfect tank are compared. The effect of geometrical imperfection on dynamic buckling is clearly shown. The PGAcr of the imperfect tank models decreases by 09.11%. Keywords Dynamic buckling  Tanks  Earthquakes  Finite element  Local geometrical imperfection  Fluid–structure interaction  Instability criteria Introduction Cylindrical tanks are among the strategic structures in daily human life. These facilities are used to store petroleum products, water, oil and chemicals, etc. According to various reports and observations on the structural behavior of the reservoirs during the recent earthquakes, steel tanks are more susceptible to damage than others. Among the past earthquakes that can be listed according to those reports are 1933 Long Beach, 1952 Kern County, 1964 Alaska, 1964 Niigata, 1966 Parkfield, 1971 San Fernando, 1978 Miyagi prefecture, 1979 Imperial County, 1983 Coalinga, 1994 Northridge, 1999 Kocaeli, 1999 Turkey (Virella et al. 2006), and 2003 Boumerde`s earthquakes. Boumerde`s earthquake (2003) occurred in the Algerian state of Boumerde`s. It was a terrible earthquake and many victims. Evidence of damage to silos Korso during this earthquake, because it was designed as not a seismic zone. Types of failure reported for these structures are dia- mond or elephant’s foot buckling, uplift of their bases, pipe damage, etc. Among these negative phenomena, dynamic buckling of tank walls remains the most common and more dangerous one (AWWA 1996). The loss of tank contents can contaminate drinking-water supplies and soil, thus resulting in serious threat to human health and environ- ment, and substantial cleanup costs. Elephant foot buckling (EFB)—which is an outward bulge located just above the tank base—results from the combined action of vertical compressive stress, exceeding the critical stress, and hoop tension close to the yield limit (Djermane et al. 2014). Elephant foot buckling bulge usually extends completely around the bottom of tanks due to the reverse in the direction of the seismic excitation (Djermane et al. 2014). Diamond buckling is an elastic instability phenomenon due to the presence of high axial compressive stresses (Djermane et al. 2014). The manufacturing process of shell production is asso- ciated with geometrical imperfection. Because of that, this & A. Chikhi chakh_fadel@yahoo.fr 1 Reliability Laboratory of Materials and Structures (FIMAS), Tahri Mohamed University Bechar, BP 417, 08000 Be´char, Algeria 123 Asian Journal of Civil Engineering https://doi.org/10.1007/s42107-018-0017-4