Study On Shear Capacity Of Reinforced Concrete Beam Based On PFC

In order to solve the problem that the cracks of the beam cannot be effectively simulated and the finite element numerical simulation cannot fully consider the inhomogeneity of the concrete structure during the calculation of the shear capacity of reinforced element beams,numerical calculation methods based on PFC have gradually begun to be proposed.Due to the complexity of the simulation of the discrete element model against shear stirrups,the current research only focuses on the study of the shear capacity of plain concrete beams,but not on the shear capacity of girders with girders.Based on the particle flow theory,this paper studies the shear capacity of reinforced concrete beams using PFC.(1)Based on the existing test data,the PFC model of C20 concrete prism specimen was established,and the concrete meso-parameters were determined by comparing with the physical test results from the stress-strain curve and crack development form;Based on the parallel bond model in PFC,the steel bar was simulated with the particles arranged in sequence,and the uniaxial tensile test was carried out to calibrate the HRB335 steel bar meso-parameters.The preparation work is made for the subsequent establishment of the PFC model of the reinforced concrete beam with web bars.(2)In order to effectively simulate the shear failure process of reinforced concrete beams,a numerical simulation method of shear stirrups was proposed on the basis of previous studies,and a PFC numerical model of RC beams with rib was established.At the same time,in order to prove the reliability of the simulation results of the PFC model,a finite element model was established accordingly,and a comparative analysis was carried out from two angles of shearing-mid-span displacement curve and crack development,to compare the advantages and disadvantages of the two numerical models in the calculation of the shear capacity of RC beams.The comparison between the PFC numerical simulation results and the physical test results shows that the PFC model has certain accuracy and reliability in the calculation of shear capacity.(3)By adjusting the main meso parameters such as contact stiffness,friction coefficient and contact normal strength,comparative analysis is carried out,and the influence of each main meso parameter on the shear force-displacement curve and the peak shear force of reinforced concrete beams is discussed;The corresponding laws of the above mesoparameters are summarized respectively,which provides the basis for the adjustment of the meso-parameters for the calculation of the shear capacity of RC beams by PFC model in the future.(4)From the shear span ratio,the concrete compressive strength,the longitudinal tensile strength of steel reinforcement ratio and stirrup,etc.,the reinforced concrete beam shear forcedisplacement curve and fracture condition are analyzed respectively,the results can be in good agreement with the relevant law of predecessors’ summary,and further verify the high feasibility of discrete element model in calculating the shearing resistance in reinforced concrete beam.