This investigation was carried out in order to understand and explain the behaviour of cylindrical shells of sandwich construction subjected to uniaxial loads with equal and unequal end eccentricities. the major object of the work carried out in the past on such composite cylindrical shells has been to study their behaviour under extemal pressure. recently, an investigation was carried out to study the use of composite cylinders as columns using grout as a filler. compared to previous work in which the sandwich cylinder was subjected to external pressure, the previous results of tests on both short composite cylinders and composite columns indicated that the steel-grout-steel composite section was less succesfull when subjected to end compressive forces. this thesis is concerned with the behaviour and strength of sandwich cylinders using micro-concrete as the filler. the results of tests on three short composite tubes, three bond-slip specimens, and six composite columns, subjected to end forces with equal and unequal end eccentricities are presented here. presents a review of previous work carried out on composite shells at the civil engineering department, university of manchester. it also includes a discussion of their aspect wich are likely to be relevant to an understanding of their behaviour when used as composite pressure vessels. a numerical analysis had been developed primarily for concrete-filled steel tubes, and work has shown that, with some modifications, it is also applicable to cylindrical shells of the sandwich construction. the theory and numerical procedure to generate the moment-thrust-curvature relationships are discussed describes the theoretical evaluation of the failure load of composite shells (steel-concrete-steel) using the finite element method. the details of the experimental investigations are reported in, where the test arrangements and details of ail tested specimens are described.