Isolation of shear strength components in reinforced concrete beams: An innovative experimental method

The shear resistance (V) of reinforced concrete (RC) beams consists of two components: contribution from concrete (V_c) and that from transverse reinforcement (V_s). Traditional tests can only provide the total shear strength V, while, till now, no existing experimental methods could isolate the V_c and V_s with reasonable accuracy. The current paper reports an experimental method that is able to quantify the two components in conventional shear tests of RC beams. This was achieved by extensive measurement of the strains in all of stirrups without disturbing the bond. Beam tests using this method show that not all the transverse bars intersecting the critical shear crack yields at the onset of shear strength. The value of V_c is not constant under increasing deformation: it first increases and slightly drops after it reaches a peak, followed by a relatively stable plateau until final shear failure.