Pull-out Shear Strength of Planar Reinforced Concrete Members

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A mechanism of failure of reinforced concrete members subjected to pull-out forces is extremely complicated and there are many problems to be made clear. It is known that the punching shear strength decreases as a loading position approaches the free edge of a member, however, the test data concerning such behavior are not enough to be applied to the design of various kinds of members. Furthermore, the effectiveness of shear reinforcement in the case of short shear span still remains uncertain.In this study reinforced concrete slab and deep beam specimens were tested. The variables investigated in the slab tests were distance from load to free edge, depth of loading position ( surface loading and embedded loading), arrangement of main and distribution reinforcements, slab width and presence of stirrups, and those in the deep beam tests were shear span-to-depth ratio, type of shear reinforcement stirrups, horizontal bars, combined stirrups and horizontal bars ) and amount of shear reinforcement.The principal results obtained are as follows; 1) In the design of planar members subjected to pull-out forces it is convenient to classify into five types of failure mechanism; beam shear with full width, beam shear with effective width, punching shear with full length of critical section, punching shear with effective length of critical section and shear of plain concrete. 2) The effect of stirrups in the case of short shear span may be less than the value estimated by the truss theory. Reduction factor as a function of shear span ratio and degree of shear reinforcement may be introduced.