Study On The Shear Behavior Of RC Beams Without Stirrups Under Asymmetric Point Load

The effect of shear-to-span ratio on the shear performance of diagonal sections of reinforced concrete beams without stirrups is significant.Reinforced concrete simply supported beams without stirrups under asymmetric concentrated loads have two different shear-to-span ratios,and there is uncertainty in the relative magnitude of shear bearing capacity and shear effect between the two shear-span sections,making it difficult to clarify the zone where shear failure occurs.The situation of asymmetric concentrated load action is more common in actual projects,but the relevant studies have been seldom reported.Therefore,it is necessary to carry out research on the shear performance of reinforced concrete beams without stirrups under asymmetric concentrated loads.The main research work in this paper is as follows:Experimental study on the shear performance of reinforced concrete simply supported beams without stirrups under six asymmetric and four symmetric concentrated loads was carried out.The failure morphology,load-span displacement curves,longitudinal tensile reinforcement strains and concrete strains in the compression zone were obtained.and the results showed that when the small shear-to-span ratio was constant at 1.0 and the large shear-to-span ratio are 2.0 to 4.0,The shear failure of reinforced concrete simply supported beams without stirrups under asymmetric concentrated loads occurred in the region of the larger shear span.When the large shear span-depth ratio increases from 3.0 to 3.5,the ultimate load capacity of the beam appears to change from large shear span section control to small shear span section control,so that the ultimate load capacity of the beam and the shear force carried by the small shear span section showed a non-monotonic change trend.ATENA software was used to carry out finite element simulations of the force performance of reinforced concrete simply supported beams without stirrups under asymmetric concentrated loads,mainly considering the effects of different shear-to-span ratios and longitudinal reinforcement ratios.It was found that the shear failure of reinforced concrete beams without stirrups under single-point asymmetric concentrated load occurred in the large shear-span section when the ratio of the calculated span to the effective height of the section 2.5<l0/h0<5.5,and in the small shear-span section when l0/h0≥5.5.The ultimate load capacity of reinforced concrete beams without stirrups under asymmetric concentrated load increases with the increase of longitudinal reinforcement rate,but the change of reinforcement rate does not affect the location of beam shear failure.the applicability of GB50010-2010,the modified compression field theory,the strain-based shear strength model and Zsutty’s formula were analyzed For reinforced concrete beams without stirrups under asymmetric concentrated load,the formula of GB50010-2010 is used to predict the location of shear failure,and the result is opposite to the test phenomenon,while the Zsutty’s formula provides a less biased prediction.