Study On Ultimate Bearing Capacity Of Reinforced Concrete Beams Based On PFC

The carrying capacity of bridges has attract much attention from scholars at home and abroad.So far,the evaluation of the bearing capacity of the old bridge is usually carried out by load test and finite element modeling.There are many limitations,such as high cost,complicated process,low calculation precision,incomplete load displacement curve and so on.In view of this highly nonlinear problem,the development and maturity of discrete element method provide a new research idea for it.In this paper,particle flow theory PFC is introduced to study the ultimate bearing capacity of reinforced concrete beam bridge.First,the establishment,development and advantages and disadvantages of the theory of particle flow are introduced.Then,on the basis of previous research and a large number of numerical simulation tests,the optimization process of the calibration of the mesoscopic parameters is put forward,and the parameters of the C30 concrete are calibrated by the uniaxial compression test.In the process of the uniaxial compression test,the load displacement curve of Zhenhai Guo and the crack development are imitated.The true calculation results are verified and the reliability of the calculation method is verified.A new calibration process is given when the parameters of the steel bar are calibrated,and the parallel bond model is developed by programming,which is specially used to simulate the properties of the steel bar and demarcate the mesoscopic parameters of the R235 bar.Before the simulation test of the ultimate bearing capacity of reinforced concrete beam bridge,the bending and shear test of the plain concrete beam is studied.The crack development process and load displacement curve of the two test models are analyzed and the analytical solution verification is carried out.The results show that it is reasonable to simulate the flexural and shear tests of concrete with PFC.On this basis,the ultimate bearing capacity test of reinforced concrete beams with notch is designed,which are divided into 10 kinds of working conditions,including no notched beams and notched beams,and the notch beams are classified according to the distribution position and inclination angle.It is found that the closer the gap is,the longer and wider the cracks are,and the shorter the cracks are,the more the cracks are.At the same time,the closer the notch angle is to 90 degrees,the easier it is to produce long and wide cracks..In addition,the error of the ultimate bearing capacity of the notched beam and the normal analytical solution calculated in this paper is 2.67%,and the load displacement curve of the notched beam is explained in four stages.The curve of the third stage is fluctuating.According to the cause of the load displacement curve,this paper refers two explanations based on the modeling calculation,one is the effect of the loading rate,and it is influenced by the loading rate.The second reason is the relative position change of the particle element.