Experimental Study On Dynamic Characteristics Of Grillage Beam Floor Under Harmonic Load

In the process of urban industrial plant construction,more and more industrial equipment is placed or moved to the top industrial workshop,equipment operation of the vibration of the floor structure has brought many problems,lighter vibration will affect the normal production,work,serious when even will make the structure vibration component cracks occur even damage,make integral structure is unsafe.In this paper,taking the abnormal vibration caused by the installation of large power equipment in an industrial factory on the fifth floor as the starting point,the scale model of the floor structure of the t-beam is designed and made.Through the scale model test,the vibration reduction effect of different reinforcement methods on the t-beam floor structure under harmonic load is studied.The test results of the scale model are verified by finite element numerical analysis,which provides a certain reference for the vibration reduction and reinforcement of the grillage beam floor.The main research contents of this thesis are as follows:（1）This thesis introduces the similarity theory of scale model test,deduces the similarity relation of parameters between the scale model of the floor of the shaft beam and the structure prototype by buckingham theorem,introduces the similarity relation of different types of scale model and the difference of different kinds of similar model,and provides theoretical basis for designing the scale model test components.（2）This paper introduces the basic situation of the floor prototype of the t-beam and the vibration test results in the field.According to the actual situation of the industrial workshop,the reinforcement method of increasing the thickness of the large floor or increasing the height of the t-beam is put forward.Referring to the design drawings of the floor structure prototype of the t-beam,and according to the ratio of the scale model to the size of the prototype is 1:4,five scale model components are designed.The making process of scale model is introduced,including the making of template,binding of steel bar,pouring and maintenance of model,etc.A steel structure loading bracket made of Angle steel welding is designed to ensure that the component is fixed with the ground,which is convenient for the installation of test equipment and instruments.The material density,elastic modulus and strength of the scale model were measured through the material performance test,and the similarity ratio between the structure prototype and the relevant parameters of the scale model test was obtained according to the determination method of the similarity relation of the scale model.The dynamic performance test of the scale model is carried out,and the dynamic signal test and analysis system DH5922 N is adopted to measure the natural vibration frequency of each component of the scale model by pulsation method.The results show that increasing the thickness of the floor and the height of the beam will affect the natural vibration frequency of the floor structure of the t-beam.But the reinforcement method of increasing the height of the well beam has more obvious effect on the natural vibration frequency of the floor structure.By load test and harmonic components under simple harmonic load vertical vibration acceleration time history curve of scale model of the dynamic characteristics analysis and comparison of different strengthening methods of vibration reduction effect,concluded that compared with increasing the thickness of the floor slab,increase the tic-tac-toe Liang Liang high reinforcement scheme of tic-tac-toe beam floor structure has better damping effect.（3）The ABAQUS finite element software was used to establish the scale model and the simulation model of the structure prototype of the i-beam floor.Through modal analysis and harmonious response analysis,the vibration characteristics of the i-beam floor were obtained,and the finite element numerical results were compared with the scale model test results.Verify the accuracy of the scale model test results and the similarity between the test results and the prototype of the t-beam floor.Through modal analysis,it can be concluded that the first-order natural frequency of the finite element model is basically consistent with the experimental frequency.The transient dynamic analysis shows that the finite element numerical analysis results are in good agreement with the model test results.Therefore,the test model meets the similarity relationship with the structural prototype,and can accurately reflect the dynamic characteristics of the structural prototype.