Finte Element Analysis Flexural Behavior Of High-strength Concrete Beams

For the size effect of the reinforced concrete beam bending property, the researchers have already done the related research in the past. However, for the ductility and the rotation ability of the reinforced concrete beam, whether there is size effect is still in dispute. In addition, the research about bending performance of the high-strength beams with double steels which are very common used still rare. In the actual reinforced concrete frame structure, the cross section of the beam ends is potential plastic hinge area, which needs adequate rotation ability and ductility. Therefore, to ensure the safety of the structure, the further research for the high strength concrete beam bending property is required. On the base of the experiments completed by other members of the group, the paper describes the further research on the size effect of high strength concrete bending performance by finite element method.The finite element simulation is executed with OpenSees and VecTor2. The project uses HRB400steel for longitudinal bar,concrete strength C70for beam.The sectional dimensions respectively are100mm x250mm,200mm x500mm,300mm x750mm and400mm x1000mm, with other parameters such as section aspect ratio, shear span ratio and reinforcement ratio parameters are consistent. The fiber element is used in OpenSees; In VecTor2analysis, finite element model based on MCFT is used, concrete element with2D plane stress element.Compared with the test results, it is discussed the effectiveness in size effcet of the fiber model in OpenSees and the2D finite model in VecTor2. Later,15beam models about different reinforcement ratio, different shear span ratio, and different concrete strength was built based on VecTor2, for the further research about size effect analysis and bending deformation performance analysis.The results show that the fiber section model in OpenSees software can simulate the bending capacity of high strength concrete beams well, but it can’t reflect size effect rule of displacement ductility coefficient, the specimens of plastic hinge ability which observed from the experiment. The main reason is the fiber model cannot reflect the size effect caused by concrete materials and the size effect caused by concrete cracking and science-induced internal force distribution. Based on the MCFT model in VecTor2, as the same as the fiber model in OpenSees, there is no consideration of the size effect from concrete materials. The2D element based on MCFT can simulate size effect caused by concrete cracking and science-induced internal force distribution well, not only with the bending performance, but also displacement ductility coefficient and plastic hinge ability to some degree. Finally, it proved the beam bending deformation capacity has a close relation with reinforcement ratio, shear span ratio and the strength of concrete based on VecTor2...