Dynamic Response Analysis And Experimental Research Of Mixed Structure Based On Complex Damping

With the process of our country’s urbanization is accelerating at present,the high-rise buildings not only increase in number and height,but also change in structural form.The single-material reinforced concrete structure or steel structure system can no longer meet the needs of high-rise buildings,and more and more mixed structural systems are being used in the design and construction of modern high-rise buildings.The mixed structures are usually composed of two or more materials with different damping properties.The damping matrix of the structure is difficult to determine.How to construct the damping matrix of the mixed structure was a problem that engineers have been concerned about.Because the viscous damping model has the simplicity of mathematical processing,and the complex damping model is easy to describe the damping characteristics of the material,these two damping theories are most widely used when solving the dynamic response of mixed structures.Although the viscous damping model is very simple in mathematical treatment,there are two problems exists:first,the energy dissipation of the first viscous damping is related to the excitation frequency and is inconsistent with the structural test results;second,this type of damping matrix is affected by the combination of vibration mode,the rationality of the results is difficult to be determined.When complex damping is used,the energy dissipation of the structure has no relationship with the excitation frequency,which is more consistent with the test results.Moreover,when we adopt the complex damping model,the damping matrix can be quickly determined according to the loss factor of the material,the calculation result is unique and is easy to determine its rationality.However,it is usually necessary to calculate the complex vibration type vector when solving the dynamic response equation of the mixed structure based on the assumption of complex damping,The calculation process is very complicated,so it is not suitable for popularizing it in engineering structure calculation.So in order to solve the dynamic response of the mixed structure,this paper proposes a forced decoupling method based on the complex damping model.The specific research contents are as follows:(1)In this paper,a forced decoupling method for hybrid structures based on a complex damping model is proposed,According to the trigonometric series method,the time-history calculation of the dynamic response of mixed structures under seismic excitation was realized.Through Matlab programming calculation,the frequency domain method based on the complex damping model,the forced decoupling method based on the complex damping model proposed in this paper and time-domain calculation method based on block Rayleigh damping are adopted for a two-degree-of-freedom and a nine-degree-of-freedom mixed structure to calculate the dynamic response,and then the calculation results obtained by using three different damping models are compared and analyzed.The calculation results show that compared with the frequency domain method based on complex damping model,the calculation accuracy of the proposed method meets the requirements and can be used for dynamic response calculation of mixed structures.Compared with the dependence of the viscous damping model on the mode combination,the proposed method obtains unique results and is easy to determine its rationality.(2)In order to further verify the correctness of the forced decoupling method of the mixed structure based on the complex damping model proposed in this paper,this paper performs a shaking table test on a mixed structure specimen composed of steel plate and damping material.And then compare the frequency response curve of the structure obtained by the experiment with the corresponding frequency response curve calculation results obtained by finite element simulation,and analyze the relative error between the test results and the simulation results.The comparison results show that the finite element simulation results of the forced decoupling method based on the improved complex damping model proposed in this paper can be in good agreement with the experimental results,thus further verifying the forced decoupling method based on the improved complex damping model proposed in this paper is corrcct.(3)In order to explore the difference between the calculated results of the hybrid structure based on the forced decoupling method based on the complex damping model and the commonly used damping method in actual engineering(blocked Rayleigh damping,single overall structure damping ratio),The author selects a light steel plus-layer mixed frame structure and a high-rise concrete filled steel tubular-light steel mixed structure for seismic time-history analysis.The comparison results show that the calculation results of the mixed structure using the block Rayleigh damping model are affected by the combination of vibration mode,and the rationality is difficult to be determined.When a single integral damping is adopted for a mixed structure,it does not consider the non-proportional characteristics of the mixed structure damping matrix,and it is difficult to give a recommended value of the damping ratio that can meet all types of mixed structures.The method proposed in this paper has unique calculation results,and can consider the influence of the non-proportional characteristics of the damping matrix of the mixed structure on the calculation results.