Title: Predicting Behavior of Condeep Storage Cells Using Classical Theory of Shells

Author(s): Amr I. I. Helmy and Michael P. Collins

Publication: Structural Journal

Volume: 114

Issue: 6

Appears on pages(s): 1457-1469

Keywords: Classical Theory of Shells; Compatibility Analysis Method; Condeep; gravity-based structure; Modified Compression Field Theory; offshore structures; reinforced concrete; shear strength

DOI: 10.14359/51700914

Date: 11/1/2017

Abstract:
A theoretical approach, based on the Classical Theory of Shells modified to account for the nonlinear behavior of reinforced concrete, is presented to calculate the deformation and internal forces in storage cells under axisymmetrical loads. An analysis method based on the compatibility conditions within the structure is presented that accounts for the material nonlinear behavior by tracking the bending moment-curvature response using the secant stiffness modulus of elasticity. The program LNADS (Linear and Non-linear Analysis of Domes and Shells) is developed based on the compatibility approach and is geared toward a flexural failure. The deformation results of this analysis were in good agreement with the experimental observations during a pressure test on a 1:13 scale model of a Condeep storage cell. The internal forces, predicted by LNADS, were used to check against imminent shear failure using the Modified Compression Field Theory, suggesting a flexural shear failure at the top of the cell wall at 423 ft (129 m) head of seawater. The program LNADS had fairly predicted the actual failure load of the 1:13 scale model. The compatibility analysis method can provide accurate predictions for the deformation and internal forces at critical sections in a storage cell, and can provide the design engineer with a quick alternative to global nonlinear finite element analysis of storage cells subjected to axisymmetric loading.