Stresses in Masonry Cylindrical Shells Using Realistic Boundary Conditions

Abstract

AbstractMasonry shells have been used as roofing since ancient times. Cylindrical and spherical shells are most common among them. They have the advantage of simplicity of construction without using elaborate support systems. Attempts have been made to use theory of shells in designing modern masonry shells. While analyzing circular cylindrical shells, the shear stress at the longitudinal boundary is frequently assumed to be zero. An earlier study by Yogananda using this assumption showed large tensile membrane stresses in the longitudinal direction. Such a boundary condition is unrealistic as the wall support is never very smooth. It appears that no axial deformation along the longitudinal boundaries is more realistic instead. Hence, the alternative condition has been considered in this paper using Flugge’s approach. The analysis results showed that the longitudinal membrane stresses are no longer tensile along the boundaries. The bending moments also show a reducing trend. Thus, the new boundary condition is well suited for designing masonry cylindrical shells. However, the diagonal tension due to in plane shear stress is increased marginally as the boundary condition is altered. The masonry shell is generally provided with a thin layer (4 cm) of cement concrete with nominal steel reinforcement both for waterproofing and for resisting settlement creeps. This will also help in resisting some of the small tension value which may occur.KeywordsMasonry shellsCylindrical shellsBoundary conditions