| In recent years,the steel-concrete composite structure has been developed rapidly.the steel-concrete composite structure combines the advantages of high compressive strength of concrete and good tensile performance of steel,which provides a wider choice for the innovation of engineering structure and difficult problems in design and construction,and has higher economic benefits.The steel-concrete composite beam often has the disadvantageous state of concrete tension and steel beam compression at the negative moment of the composite frame structure system.As a secondary stress member,the floor is often not considered in the basic structure,and its anti-seismic effect is easy to be ignored.In this thesis,the installation of Asymmetric Friction Connections(AFCs),in composite beams can reduce the cracking of concrete slabs and strengthen the energy dissipation capacity of composite beams.In this thesis,the working mechanism and design method of asymmetric friction connectors of steelconcrete composite beams are studied by means of experimental research and finite element analysis.The experimental design consists of two parts:(1)low cycle reciprocating loading test of asymmetric friction joints of waste brake pads,and(2)reciprocating loading test of friction joints of steel-composite beams.Seven groups of specimens were designed and made,and their seismic performance was studied by low cyclic loading test.The results show that the hysteretic curve formed by the designed AFCs device with waste friction plates has obvious double-step energy dissipation,and maintains a good sliding friction force under cyclic loading,and the hysteretic curve is stable and full,which is conducive to the realization of the second-order seismic fortification goal.The bearing capacity and stiffness of the specimens with large pretension are also increased,and the loss of pretension and friction coefficient do not change much,indicating that the waste friction plate has better performance as a friction material.Then the AFCs device is applied to the composite beam as a shear connector.In order to study the seismic behavior of steel-concrete asymmetric friction connections,considering bolt diameter,bolt pretightening force and friction gasket material factors,reciprocating loading tests of 7 groups of AFCs steel-concrete connections were carried out.The test results show that except for the large deformation of the aluminum friction plate specimen in the loading process,the hysteretic curves of each specimen have little difference and are full,which can form an obvious double slip platform and realize the expected asymmetric friction energy dissipation;the increase of pretightening force and bolt diameter increases the bearing capacity,stiffness and energy consumption obviously,and the stiffness degradation of the specimen is obvious in the early stage of loading and tends to be smooth in the later stage.The hysteretic curve of brass friction plate is the fullest,the bearing capacity and energy dissipation capacity are the best,followed by wear-resistant steel friction plate,aluminum friction plate has the worst energy consumption,and the properties of wear-resistant steel and brass friction plate are similar.The use of wear-resistant steel can save cost.On the basis of the experimental research,the PSC-2 of the specimen is modeled and analyzed by using the finite element software ABAQUS,and the skeleton curve of the specimen is obtained.the results show that the finite element simulation results are in good agreement with the experimental results.Through the finite element parameter analysis,the modeling analysis of the aperture ratio of the specimen shows that the loop area formed by the hysteretic curve of the model does not increase obviously,but it can improve the length of the double slip platform,indicating that the higher the aperture ratio,the more obvious the sliding effect of the AFCs double platform. |
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