| Corrugated web steel box-concrete composite girder is an improvement of the traditional composite box girder with corrugated steel webs.The concrete bottom plate of the traditional composite box girder with corrugated steel webs is replaced by the steel bottom plate with a stiffener of about 20 mm,which forms a new steel-concrete composite structure with lighter self weight,more reasonable stress and stronger durability.In recent years,many scholars have carried out a lot of research work on the dynamic characteristics of the traditional composite box girder with corrugated steel webs,but as a new type of structure,the dynamic characteristics of the corrugated web steel box-concrete composite girder have not been studied in depth.In this paper,theoretical analysis,numerical simulation and experimental methods are used to study the dynamic characteristics of corrugated web steel box-concrete composite simply supported girder and corrugated web steel box-concrete composite continuous girder.The main work and research results are as follows:(1)Considering the shear lag effect of box girder and the shear deformation effect of corrugated steel web,the element stiffness matrix and element mass matrix of corrugated web steel box-concrete composite girder are derived by using the potential energy stationary value theory.The program for calculating the vertical bending natural frequency and mode of the corrugated web steel box-concrete composite simply supported girder is compiled by using MATLAB finite element software.The correctness of the program for calculating the natural frequency and mode shape of vertical bending of simply supported girder is verified by the test data and the three-dimensional finite element value of ANSYS,and the convergence speed of the program for calculating the natural frequency and mode shape of vertical bending is analyzed.The results show that only a small number of elements are needed to solve the vertical bending natural frequency and mode shape of the corrugated web steel box-concrete composite simply supported girder by the method in this paper,which can achieve high calculation accuracy,greatly shorten the calculation time of the vertical bending natural vibration characteristics,improve the calculation efficiency,and avoid the complexity of the establishment and solution of the three-dimensional finite element model of ANSYS.(2)Based on the verified program for calculating the vertical bending natural frequencies of corrugated web steel box-concrete composite simply supported girder,the influence law of the creep effect of concrete top slab,the thickness of steel bottom plate and corrugated steel web,the model,the calculated span,the ratio of height to span,the ratio of width to span and the ratio of overhang to wing of corrugated web steel box-concrete composite girder are analyzed.The results show that: the vertical bending fundamental frequency is greatly affected by the thickness of steel bottom plate,and less affected by the thickness of corrugated steel web.The vertical bending natural frequency of corrugated web steel box-concrete composite girder is less affected by the shear lag effect of box girder,and more affected by the shear deformation effect of corrugated steel web.(3)According to the element stiffness matrix and element mass matrix of the corrugated web steel box-concrete composite girder,the program for calculating the vertical bending natural frequency and mode shape of the corrugated web steel box-concrete composite continuous girder is compiled by using MATLAB finite element software.The calculated value of the program is in good agreement with the three-dimensional finite element value of ANSYS and the measured value of the indoor model test beam,which verifies the correctness of the program,and analyzes the vertical bending natural vibration characteristics of the constant cross-section continuous girder and the constant cross-section continuous girder.The results show that when the span of equal span and equal section corrugated web steel box-concrete composite continuous girder is the same as that of simply supported girder,the vertical bending fundamental frequency of continuous girder does not change with the number of spans,and the k-th vertical bending mode of simply supported girder is just the [1+(k-1)n]-th of n-span continuous girder.The vertical bending natural frequency of corrugated web steel box-concrete composite continuous girder with unequal span and equal cross section increases with the decrease of the ratio of side span to mid span,and the higher the frequency,the faster the growth. |
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