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The behavior of reinforced concrete beams at failure by shear is distinctly different from their behavior by bending, which is considered to be unsafe mode of failure. The shear failure of beams is usually sudden without sufficient advanced warning and the diagonal cracks that develop due to excess shear forces are considerably wider than the flexural cracks. The cost and safety of shear reinforcement in reinforced concrete beams led to the study of other alternatives. Swimmer bar system is a new type of shear reinforcement. It is a small inclined bars, with its both ends bent horizontally for a short distance and welded to both top and bottom flexural steel reinforcement. Regardless of the number of swimmer bars used in each inclined plane, the swimmer bars form plane-crack interceptor system instead of bar-crack interceptor system when stirrups are used. Test results of several reinforced concrete beams will be presented. The effectiveness of the new swimmer bar system as related to the old stirrup system will be discussed. Beam deflection is also targeted experimentally in the lab. Several deflection measurements were taken to study the effect of using new swimmer bar system on deflection. Also the crack width of the tested reinforced concrete beams was monitored.

Abstract--The sudden nature of shear failure in reinforced concrete beams is undesirable and requires special attention. This undesirable mode of failure pushes the design engineers to use higher factor of safety against the shear forces. Several alternatives to the traditional stirrups were introduced in the past including the concept of the swimmer bars. This study focuses on special kind of swimmer bars. The new swimmer bars system used in this study is called space swimmer bars system which requires no welding to be assembled. The space swimmer bars concept is new and effective in improving the shear performance of reinforced concrete beams. The results of this study will be compared with the traditional stirrups, as well as the welded swimmer bars. The space swimmer bar is basically a reinforcing bar bent several times in the three dimensions forming special configuration along with its coupling swimmer bar. This configuration makes the shear reinforcement system act as plane-crack interceptor rather than linear bar-crack interceptor. This new system is not only effective in taking care of the shear forces, but also it is economical compared to the traditional stirrups and the welded swimmer bars. There is no available data to show the performance of the welded swimmer in the long run, but this new type of swimmer bars system requires no welds. In addition, welding shear reinforcement bars does not seem to be desirable in the construction engineering practice. Several beams will be tested. One group of beams are reinforced with standard traditional stirrups as shear reinforcement and they are used as control samples. The second group of beams used welded swimmer bars as shear reinforcement system. The third group of beams used the new space swimmer bars as alternative to the existing shear reinforcement systems in reinforced concrete beams. The results of the three groups of beams will be presented. Flexural cracks as well as shear cracks will be monitored with the increase in the applied load. The deflection at the mid-span of the beam will also be monitored as the applied load is gradually increased.Keyword-Space swimmer bar, Deflection, Shear, Crack, Stirrup I. INTRODUCTION The main objective of the design of reinforced concrete beams is safety. The sudden failure mode requires higher factor of safety. The design engineer has to make sure that the mode of failure is acceptable and gives enough warning before failure. The shear failure is not one of the desirable mode of failures and should be avoided. Reinforced concrete beams are one of the common structural elements that carry transversal loads mainly by flexure and shear. The common design approach is to design the beam for flexure then design the beam for shear. The available design codes emphasizes on the ductile flexural failure by reducing the amount of steel reinforcement in the tension area, in order to make sure that the longitudinal tension bars yield first. While the design for shear focuses on providing enough shear resistance exceeding the ...

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Abstract:In many places of the world, water is a scarcity resource. The possibility of reusing water increases the relevance of developing different water treatment methods. The goal of this research was to determine if the photo-Fenton processes are efficient for the degradation of organic compounds, as a possible alternative for wastewater treatment. In order to carry out this study, different catalysts were characterized by different techniques (XRD, FE-SEM, SBET and TGA) and catalytic tests. Iron oxide nanowires (Fe 2 O 3 NWs) and a commercial catalyst (FeCl 2 ) were tested in the methylene blue photo-Fenton degradation reaction. The catalysts used were able to degrade the methylene blue and could eventually be used to remove contaminants from the water.