Behaviour of composite conical tanks under hydrostatic pressure

Abstract

Conical vessels are used around the globe for liquid storage in water tanks. These vessels can be made of steel, reinforced concrete, or composite; i.e. concrete and steel. Composite vessels consist of an external steel shell attached to an internal reinforced concrete wall through steel studs. Previous studies available in the literature focused on studying steel or reinforced concrete vessels. To the best of the author’s knowledge, this paper presents the first comprehensive study conducted on liquid-filled composite tanks. A Finite Element Model for Composite tanks (CFEM), which accounts for both the geometric and material nonlinearities, is developed. The material nonlinearity is considered by including nonlinear models for both steel and concrete. The developed CFEM also considers nonlinear behaviour of studs by including the nonlinear load-slip and load-peel curves obtained from test results reported in the literature. In the CFEM, both the concrete and steel walls are modelled using 13-node subparametric shell elements, while the connecting studs between the two walls are modelled using 26-node contact elements using a smearing approach. Validation of the CFEM is conducted by modelling two composite slabs from the literature and comparing the results with their counterparts obtained from the conducted experiments. The CFEM is used to evaluate the deflections, stresses, and internal forces in the concrete and steel walls as well as steel studs. An Equivalent Section Method (ESM) for the analysis of composite tanks, which is based on using an equivalent single wall, is introduced. Deflections, stresses, and internal forces in the steel and concrete walls predicted using this simplified approach are compared to those predicted by the detailed finite element model.