ملخص الدراسة:

In comparison with the option of “demolish and rebuild buildings”, sustainability can be better achieved by extending the life spans of existing structures. Rehabilitation of structures results in less construction waste materials, reserves natural resources, minimizes adverse environmental effects, saves time, saves cost, etc. The structural behavior of reinforced concrete beams strengthened with concrete jackets or steel plating has been investigated in the undertaken research both theoretical and experimental. The main aim of the research is to demonstrate the best among the investigated strengthening techniques. The experimental work included testing of 26 reinforced concrete beams divided into two series. The first series contains 13 beams proposed to have inadequate flexural capacity and the purpose is to increase it. While, the second series contains 13 beams with low shear capacity because of inadequate amount of stirrups and the purpose is to prevent the shear failure. Strengthening operation has been accomplished using concrete jackets or steel plates with different configurations. The test variables included the type of strengthening (shear or flexural), the technique of strengthening (concrete jacketing, steel plating) and the type of connections to prevent laminar shear between the old concrete and the strengthening elements (mechanical or chemical). As predicted, the strengthened beams exhibited different structural behavior upon loading up to failure. The beams strengthened with mechanically bonded concrete jackets showed best structural behavior. The beams strengthened with chemically bonded concrete jackets showed good results, especially in the case of three-face jackets. The beams strengthened with chemically bonded steel plates exhibited sudden brittle failure upon debonding of the plates from the beams at ultimate load levels. The beams strengthened with mechanically connected steel plates have not achieved the expected level of enhancement because of pre-mature debonding of the steel plate or buckling. Better results may be achieved by using a combination of mechanical and chemical bonding especially at the end of jacket or plate. Steel straps bonded at the outerface of the beam can prevent the shear failure and recover the flexural capacity while continuous steel plates bonded to both sides of the beam can only delay the shear failure with increasing in flexural capacity. In conclusion, strengthening of existing beams can be effectively achieved using practical techniques, which will increase the life spans of the beams and thus enhance the sustainability of existing structures.

توثيق المرجعي (APA)