EFFICIENCY OF INTERNAL STRENGTHENING R.C BEAMS WITH RECTANGULAR OPENINGS IN SHEAR ZONE BY USING STEEL PLATES

Abstract

The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts results not only in a more systematic layout of pipes and ducts; but also translates into substantial economic savings in the construction of a multi-storey building. Over the past several decades, many researchers exerted great efforts to predict and interpret the behavior of beams with web openings [3-9]. They recommended convenient methods for the design of such beams. External strengthening by using external steel plates or external CFRP laminates will be a satisfactory method in the case if it is required to provide new opening in existing beams. In this research it was suggested to use internal steel plates to improve the efficiency of beams with opening. Therefore, twelve R.C beams were tested under static loading up to failure; eleven of them were fabricated with rectangular opening through the web in shear zone while the remaining beam had a solid web. Internal steel plates around the opening were used in strengthening them. The effect of internal steel plate's thickness, and configuration, horizontal steel plate length and concrete grade is investigated. The pattern of cracks and modes of failure were observed. The mid span deflection, the inner edge of opening deflection and the difference between deflections of the two opening edges were measured. The crack and ultimate load were recorded. The results were studied and given in shape of plates, tables and curves.