This paper presents comprehensive test data on the effect of glued steel plates on the first crack load, cracking behaviour, structural deformations, serviceability loads, and ultimate strength, of rein forced concrete beams strengthened with such plates on the tension face. The results show that plated beams have enhanced flexural stiffness which control cracking and deformation at all load levels until failure. However, the stiffening effect is much greater in controlling cracking; further, the structural effect is far greater than if the bar area had been increased by the same area as the plates. Provided the adhesives are chosen carefully and proper gluing techniques are followed, the plated beams show beam action and composite behaviour right up to failure. The glued plates can increase the ultimate flexural strength by up to about 15 %. There is, however, a limit to plate thickness beyond which premature shear/bond
failure occurs without the beams achieving their full flexural strength, even though such beams still control cracking and deformation until failure. The paper suggests two tentative design criteria to ensure full flexural capacity and ductile failure of plated beams.
R.N. Swamy, R. Jones and J.W. Bloxham