The Research Of Shear Bearing Capacity Of Reinforced Concrete Deep Beam Based On The Softened Strut-and-Tie Model

Since the beginning of the 20th century, research on shear performance of reinforced concrete deep beam has been explored. The shear mechanism of reinforced concrete deep beam is complex and there are many impact factors on it. The most code provisions are principally empirical, and do not set up a theoretical system that relatively uniform and complete, including our country. Therefore, it is necessary to do further research of reinforced concrete deep beams.Design method of deep beam shear bearing capacity was respectively analyzed based on the code of GB-10、ACI-11 and EN-98 in this paper. The results showed that the calculated value of strut-and-tie model (STM) method in the code of ACI-11 and EN-98 was significantly closer to the experimental value than the calculated value in the code of GB-10.The further study in this paper found that the STM method didn’t get many details of that the concrete softening phenomenon existing in deep beams after cracking. But the softened strut-and-tie model (SSTM) method can make up for the shortage. However, the SSTM method was too complex to hand computation, and the softening effect were not taken into account comprehensively, so the strut-and-tie coefficient K was introduced to simplify the calculation in this paper, and the coefficient was revised as .Comparing the modified SSTM method with the SSTM method and the method in three codes, a conclusion was drawn that calculation value of shear bearing capacity with the SSTM method was most closest to the test value, which showed the superiority of the SSTM method.According to the modified SSTM method, the influence on shear performance of reinforced concrete deep beam was analyzed using the finite element software ABAQUS, and the influence factor included the concrete strength grade, span ratio, shear span ratio, vertical web reinforcement rate and the longitudinal reinforcement ratio.Finally, combining with the modified SSTM method, the shearing capacity formula in code GB-10 was modified in this paper, was changed to The calculation values of the modified formula coincided well with the test results.