Shear Strengthening of Pretensioned Prestressed Concrete Composite Flexural Members.

摘要

Strengthening is required due to inadequacy which typically results from a poor design, a change in usage, or a change in design loads. Prestressed composite beams require special attention in connection with their behavior in horizontal shear at the composite interface. Beams lacking adequate shear reinforcement experience brittle shear failure unless they have low flexural stiffness. Such beams can be strengthened so that they can develop their flexural capacity and behave in a more ductile manner at failure. External post-tensioning system is often a desirable strengthening solution when a major portion of a member must be strengthened or when the cracks which have formed must be closed. The research work studies the behavior of retrofitted prestressed composite beams that originally lacked shear reinforcement and have a smooth interface bonded with epoxy. Before retrofitting these beams experienced sudden horizontal shear failure. Ductile flexural failure occurred after being retrofitted by external prestressing bars. The research studied how the mode of failure of prestressed composite flexural member could be changed from a sudden shear failure to a ductile flexural failure by utilizing external prestressing bars.