| 8 reinforced concrete simply-supported beams with web reinforcement, with shear span ratio being 1.5 and longitudinal reinforcement ratio varying, were analyzed using nonlinear finite element analysis program, VT2, based on modified compression filed and disturbed stress field theory. The tested and analyzed results were compared including load-displacement relationship, failure models, and longitudinal reinforcement strains. The stress field of concrete was thus deduced. In the mean time, the effect of longitudinal reinforcement ratio was also discussed.A simplified model, the strut-and-tie model in Appendix A in ACI318-02, was used to check its validity in predicting the load capacity and failure model. Analytical results indicate that the analytical results are accurate for the beams failed in shear. The prediction of ultimate shear strength is within 8 % comparing with the tested results. But the differences in stiffness, deflection in the mid-span are significant. The more the longitudinal reinforcement ratio is, the more the differences are. By comparison of longitudinal reinforcement strains, it is shown that the maximum value of strain occurred at the interaction of the longitudinal reinforcement with the critical inclined crack. Development of critical inclined crack could not be simulated using smeared crack model. The analytical results are less accurate for the beams failed in flexure, with the difference in ultimate bearing capacity being at least38%. Before the flexural crack initiates, tested and analytical strains of longitudinal reinforcement are very close. The gap is widening after the flexure-shear inclined crack appears. It is less accurate when modeling the failure model using strut-and-tie model. The ultimate loading capacity calculated with strut-and-tie model is 50 %less than tested results. The calculated results of beams failed in shear using strut-and-tie model are close to the tested results but the beams failed in flexure are less than tested results.
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