Stress Analysis And Experimental Study Of Large Tonnage Prestressed Anchor Zone

In the development of domestic large-span prestressed concrete continuous girder bridges,the local stress distribution law of the box girder anchoring area is a content that needs to be researched,and it is also an important experimental research project in the process of bridge construction.Now taking a new railway project(110+228+110)m continuous beam-arch composite structure bridge as the engineering background,the method of combining finite element simulation analysis and experimental research is used for research.In order to verify whether the test model is safe for concrete in the anchorage area under large tonnage prestressing loads and whether adjacent tunnels have cracks due to stress diffusion,and to verify that the design of the anchoring area of the solid bridge is reasonable and safe,a full-scale model is used to represent The design of the anchoring zone structure is concentrated on a test model,combined with finite element simulation,and the test is carried out according to the test plan to study the stress,distribution and transmission of concrete in the anchoring zone.The main research contents are as follows:(1)Design the test model.By analyzing the structural stress conditions of the typical anchoring zone in a solid bridge,and combining relevant conditions such as the steel beam specifications and the size of the anchoring force,the tensioned steel beams T0,T2,T4,T7,T10,T17,F8 that need to be analyzed and studied-F12,based on the same ideas as the real bridge,these different types of tensile steel bundles are collectively designed on the same experimental model for research.(2)Establish a linear elastic finite element model and calculate and analyze it.According to the designed test model drawing,use the finite element software Midas FEA to establish a linear elasticity calculation model,from the establishment of the geometric model,the mesh division,the applied load,the definition of the boundary conditions,the transformation of the coordinate system to the post-processing analysis and calculation results,etc.The modeling and analysis process is described,and the calculation results show that the stress distribution in the anchoring zone of the test model is consistent with the stress distribution in the anchoring zone of the solid bridge,which can be used to conduct experimental research on behalf of the anchoring zone of the solid bridge.(3)Carry out the prestressed load test in the anchorage zone.According to the test plan,the test data was collated and summarized,and analyzed and compared with the calculated value data.The results show that: the stress distribution of the concrete in the anchorage zone in the actual test of the test model is the same as the calculated value analysis,the measured data and the finite element calculation data It is relatively close,the difference is basically within 2 MPa,and the stress change trend is basically the same.The reason for the cracks in some anchorage areas is that the concrete is not vibrated compactly,which is not related to the design of the anchorage area.The design of the solid bridge anchorage area is relatively reasonable and reliable.