Experimental Study On Flexural Behavior Of Beams With Bundled HRB500 Bars

Steel bars are allocated intensively in the transfer beam of reinforced concrete structures and components such as beam slab on the civil air defence works. It is difficult to position steel bars and to cast concrete at the locations. An effective way to handle this problem is to use bundled bars, namely, to bundle two or three deformed bars abreast. In high strength reinforced concrete member, due to the increase in reinforcement stress,may produce larger cracks.The influence of Reinforced Concrete with bundled high strength bars should be further studied.The paper is an experimental Study on flexural behavior of beams with bundled HRB500 bars, evaluate the use of formula of current codes GB50010-2010, including ultimate strength, fracture spacing, crack width and deflection and so on.The results showed that: beams with bundled HRB500 bars and single reinforcement beam similar exhibit typical damage characteristics of elastic stage, crack development stage and failure characteristics. Calculated values of ultimate strength with bundled bars beam and single reinforcement beam find the same, were in line with the requirements of specification. The bundled bars converted to single reinforcement of equivalent diameter with principle of area equivalent. The deflection values obtained in the experiment of concrete beams reinforced with bundled HRB500 bars are close to those values obtained according to the current code GB50010-2010. The average crack wideth and the short-term maximum crack wideth values obtained in the experiment were less then the current code calculated value. Which the short-term maximum crack wideth formula and the average crack wideth formula of the current code should be modifyd is adviced.