A risk‐targeted seismic performance assessment of elephant‐foot buckling in walls of unanchored steel storage tanks

Abstract

Unanchored steel storage tanks are used in industrial plants to store oil and other petrochemical liquids. In a major earthquake, such tanks may sustain different types of damage, including elasto‐plastic buckling in the shape of an elephant's foot, which is the object of the research. The methodology introduced in this paper consists of cloud‐based 1D site response analysis (SRA) and pushover‐based seismic performance assessment of the tank wall using a 3D non‐linear model of the tank. The SRA, which considers the recorded ground motions on the rock outcrop and the sample of interval shear‐wave velocity profiles, is carried out to estimate spectral accelerations at the tank impulsive period. By adopting the code‐based model of hydrodynamic pressures, the seismic demand on the tank wall is then calculated by pushover analysis. The risk‐targeted decision model is used for safety verification. The proposed methodology is demonstrated through an example of a large liquid storage tank for which it is shown that the fragility function for peak ground acceleration at the rock outcrop is on the left side of the target fragility function, indicating that the tank cannot be considered safe from elephant‐foot buckling. The introduced assessment process is relatively simple if the cloud‐based SRA is automated. However, further experimental and numerical investigations are required to confirm the validity range of the pushover analysis for the seismic performance assessment of tanks.

State-of-the-Art Review on the Seismic Performance Assessment of On-Ground Steel Cylindrical Tanks

“…They studied the influence of various arrangements of circular cutouts on the buckling and post-buckling behavior of cylindrical shells. In addition to the above studies, several others provide significant insight into the buckling of tanks via the static numerical procedures [103][104][105].…”

Risk‐targeted seismic design: Prospects, applications, and open issues, for the next generation of building codes

“…The topic of design methods alone occupies one‐third of the papers, which is not surprising given the scope of the SI. The papers by Ahmadie Amiri and Estekanci, 11 Chen et al., 12 and the two by Dolsek and co‐workers, 13,14 deal with the risk‐targeted design of specific structural types, while those of Fox and O'Reilly, 15 Kourehpaz et al., 16 Clemett et al., 17 and Hulsey et al., 18 with the role of seismic vulnerability (i.e., fragility) in risk‐targeted design. A few papers deal with more specific issues, such as non‐structural elements (i.e., Merino et al.…”