Study On Simply Supported Composite Beam Of Assembled Steel-High Performance Cement Matrix Composites

The prefabricated Steel-High performance cement composite composite beam is a composite structure,in which the prefabricated concrete roof and the steel beam are assembled together in the field through shear connectors.Compared with the traditional concrete beam bridge,the assembled Steel-High performance concrete composite structure can realize factory construction,ensure construction quality and shorten construction period.It can also give full play to the mechanical properties of high-strength materials,reduce the weight of the structure,reduce the height of the cross-section and increase the clearance under the bridge,so as to achieve the purpose of saving materials and reducing costs.Therefore,the mechanical properties,microstructure,shear stiffness of stud connectors and static response of composite beams of high performance concrete are studied by means of experimental method in this paper.The purpose is to lay a foundation for further application and development of assembled composite beams,and the main research results are as follows:1.In material research,based on the optimum steel fiber content,the working performance and mechanical properties of cement-based composites with steel fiber and basalt fiber are studied by using equal volume replacement method.The results show that with the increase of substitution ratio of basalt fibers,the performance of cement-based composites is improved obviously.When the substitution ratio reaches20%,the compressive and splitting tensile strength of hybrid fiber cement-based composites reaches the maximum,112.3MPa and 20.07 MPa,respectively.In addition,the use of scanning electron microscopy and IPP image processing technology to analyze the microstructure of the material shows that reasonable fiber content can effectively improve the internal structure of the matrix,and the anti-cracking effect of fiber reinforcement also greatly improves the anti-deformation ability of the matrix.2.In order to investigate the failure mode,shear stiffness and ultimate bearing capacity of stud connectors in assembled steel-concrete composite structures,six groups of studs with different sizes are studied and analyzed by push-out test.The results show that the ultimate failure of the six groups of specimens is terminated by bolt shearing;the secant modulus corresponding to the maximum shear force of 1/3is more reasonable;and the ultimate bearing capacity increases with the increase of bolt diameter.ANSYS is used to simulate and analyze the push-out test,and it is found that the two results are in good agreement.3.In this paper,the assembled steel-concrete composite simple-supported beam is studied and analyzed by means of two-point symmetrical loading method.The results show that the maximum displacement of composite beams reaches 56.91 mm when the ultimate load is 140.28 kN,and the deformation of mid-span section still conforms to the assumption of plane section when the load is less than 100 kN.The shear-slip strain difference at the interface increases with the increase of the load,resulting in a large deviation at the loading position.3.In addition,the numerical model is obtained by using ANSYS simulation technology,which is in good agreement with the experimental data,thus providing a more convenient and effective method for the study of assembled composite beams.