Effect Of Longitudinal Reinforcement Distribution On Shear Behavior Of Deep Flexural RC Beam When Shear-Span Ratio Is 1.5

Available test data from systematic investigation for effect of longitudinal reinforcement ratio on shear behavior of RC beams is relatively rare. A majority of previous studies on the effect of longitudinal reinforcement ratio on shear behavior of reinforced concrete members concerned about beams without web reinforcement; few gave detailed recording of strains of reinforcements in the development of cracks up to failure.Therefore,desirable objective measurements in evaluation of failure mechanism are scarce.Twelve simply supported beams with different amount of longitudinal reinforcement, with or without web reinfocement, were tested under monolithic two-point loading, with the shear-span ratio being kept around 1.5. Overall development of cracks, failure mechanism, strain distribution of reinforcement and ultimate capacity of these beams were investigated. The width of cracks, together with strains on the longitudinal reinforcements and deflection of the beams were carefully measured. Furthermore, correlation between the measured strain profiles of the longitudinal reinforcement and the observed cracking development of each specimen was investigated. Dominant factors governing the cracking process and failure mode were figured out as a result.On this basis,nonlinear finite element analysis using the software VecTor2,which is based on the so called MCFT (Modified Compression Filed Theory)model and DSFM(Disturbed Stress Field Theory)model, was carried out for the tested specimens.Comparison of the results show the validity of the models.â‘ With the increment of longitudinal reinforcement ratio, the failure mode of beams without web reinforcement changes from flexural failure to shear failure, ,the shear slip at cracks when failure occurs is significant. The more higher the longitudinal reinforcement ratio, the more significant the shear slip.â‘¡Shear capacity of singly-reinforced deep flexural beams without web reinforcement increases with the increase of the longitudinal reinforcement ratio.The singly-reinforced beams with web reinforcement show the same tendency.â‘¢On the other hand, while the shear hear capacity of doubly-reinforced deep flexural beams without web reinforcement increases with the increase of the longitudinal reinforcement ratio, the doubly-reinforced beams with web reinforcement...