Rehabilitation of elliptical parabolic reinforced concrete shells with openings

As the using of reinforced concrete shells structures with opening have many advantages that they permit to cover large area without using intermediate supports. They have light weights and require minimum amounts of material that it is required small thicknesses comparing to their spans. This investigation is carried out to study the efficiency of repair and strengthening of elliptical parablooid reinforced concrete shells, which loaded by four concentrated loads at the center of the opening. An experimental program of several different techniques in repair and strengthening is executed. The materials, which are considered for strengthening, are; Glass fiber reinforced polymers GFRP at different position of the shell bottom surface, steel strip and external tie. The initial and failure loads as well as the crack propagation for the tested shells at different loading stages, deflections and failure load for repaired and shells are recorded. A non-linear computer program based on finite element techniques is used to study the behavior of these types of shells. Geometric and materials nonlinearities are considered in the analysis. The efficiency and accuracy of computer program are verified by comparing the program results with those obtained experimentally for the control shell with opening and strengthened shells.