The Research On R.C. Beam Strengthened By Externally Bonded And Anchored I-Section Steel

In the field of industry and civilian structure, concrete beam is widely used, and is important among all of the structural members. During used, concrete beam is consolidated frequently because of insufficiency of bearing capacity. Increasingly, the method of strengthening by externally bonded steel plates is paid attention to many people, by reason of many virtues, for example, light of self weighted, small of volume, short period of construction and so on. More and more profitable experiments and research on strengthening by externally bonded steel plates of reinforcement structure are carried out by many scholars and engineering technician.On the base of previous research, the bending behavior of RC beams strengthening by externally bonded and anchored I-section steel is discussed in this paper further more, Three parts of this paper are follows:First part: mechanical behaviour and failure pattern are analyzed in the condition of full bond (with no relative deformation) with I-section and RC beam, and influence of unloading degree in this part. When critical of beam occurred, the balanced depth of the compression zone the maximum steel ratio the maximum height of I-section steel and the minimum degree of unloading are provided, the theory formula of bearing capacity correspondence to failure pattern is erected, and the influence of failure pattern and bearing capacity to unload degree initial ratio of reinforcement is analyzed, and the appropriate simple calculate and process of design in engineering employ are submitted. In the condition of large the initial reinforcement ratio and the temperamental unloading degree, advice is given that strengthening by externally bonded and anchored I-section steel is avoided.Second part: In the condition of considering of bold-slid, the formula of interface stress is erected, and the influence of unloading degree to direct shear stress is analyzed, and the conclusion is made out that initial load is propitious to stress of interface. On this base, the theory formula of relative slipping strain of middle span section is erected, and the influence of slipping effect to the failure pattern of reinforcement beam is discussed, and the conclusion is made out that structural member is easy to be brittleness destroy in condition of considering slipping. Base on the relative slipping effect, the theory formula of additional moment that is derivable from slid action, and the influence of the thickness of glue unloading degree the ratio of I-section steel to additional moment is discussed.