Performance-based design of thin-walled fluid storage tanks: an alternative to meet the requirements of the proposed standard pr-NCh2369

Abstract

In 2021, the public consultation period for the modification project of the Chilean Standard for Seismic Design of Industrial Structures and Facilities ended. This project, called pr-NCh2369, will soon replace the currently valid NCh2369 (2003). This article evaluates the implications that these modifications will have on the analysis and design of thin-walled fluid storage tanks. Among the most noteworthy aspects we can mention: (1) an elastic reference spectrum is defined (which did not exist in the previous version), which can be used to carry out special analyses and also to incorporate seismic protection systems, either energy dissipation or seismic isolation; (2) it is established that the design base shear of the previous version is a minimum base
shear, therefore, the new tanks with conventional anchoring system would have an equal or higher base shear demand; (3) where applicable, soil-foundationtank interaction should be explicitly included in the model; and (4) structures susceptible to premature
failure due to buckling (elastic or elasto-plastic) must be analysed with the reference elastic spectrum (R = 1). In order to facilitate the application of this proposed regulatory amendment, a general methodology based on performance based criteria is presented, which can be applied to anchored and unanchored tanks, as well as to tanks with dissipative anchors, also considering
circular and annular type foundations.