Analysis Of Flexural Performance Of Long-Span Unbonded Prestressed HSFRC Beam

With the rapid development of society,the pursuit of more efficient structural forms to achieve larger spans will inevitably be the development direction of concrete structures in the future.The emergence of HSFRC materials has played a huge role in achieving this goal.However,currently,the research on the constitutive relationship of the new material HSFRC is far from enough.A further experimental studying of the performance of large-span unbonded prestressed HSFRC beams is very necessary.Moreover,the research on the parameters that affect its bending performance is still insufficient.In response to the above problems,this thesis is on the base of the bending test results of the long-span unbonded prestressed HSFRC beam with a length of 21 m,the theoretical analyses and finite element program simulation study were conducted and a co MParison is made according to the results.The parameters affecting the flexural performance of long-span unbonded prestressed HSFRC beams have been simulated and studied.The specific work is as follows:(1)The current results of the mechanical properties of HSFRC materials are thoroughly analyzed and discussed.On this basis,a material constitutive model suitable for HSFRC with the steel fiber content 2% is proposed and applied to the theoretical analysis and finite element simulation on long-span HSFRC beams;(2)The simulation methods of unbonded prestressed tendons in the finite element program were studyed.The finite element simulation of the curved unbonded prestressed tendons with the local coordinate Coupling Method served to verify the effectiveness of the model;(3)Numerical calculations were carried out using the parameters of non-prestressed reinforcement ratio,unbonded prestressed reinforcement ratio and jacking stress in the tension zone of large-span unbonded prestressed HSFRC beams.The cracks in the tensile zone,loaddisplacement curve and stress increments of unbonded prestressed tendons were chosing to analyze the influence of above parameters on the bending performance of the beam.