Research On Optimization Of Viscous Dampers In Concrete Frame Structures

When the earthquake occurs,many buildings are damaged because of large inter-story deformation or large shear force at the bottom.In order to reduce the seismic response of structures,viscous dampers have been installed in more and more buildings in recent years.When viscous dampers are installed in reinforced concrete frame structures,the inter-story displacement angle and shear force are affected by the location and parameters of dampers.Therefore,the location optimization and parameter optimization of dampers deserve further study.Vector Form Intrinsic Finite Element(VFIFE)method is a numerical calculation method based on Newton's law of motion.The calculation procedure is simple and the amount of calculation is small.Genetic Algorthm(GA)is an optimization method which imitates the evolutionary mechanism of organisms in nature.It has the nature of parallel and global search,so it has high optimization efficiency.Based on the VFIFE theory,this paper compiles the MATLAB program,and uses GA to study the position optimization and parameter optimization of dampers for concrete frame structures whose deformation meets or does not meet the requirements of codes.The main contents of this paper are as follows:(1)In this paper,the VFIFE theory is elaborated,and the formulas for calculating the internal and external forces of frame structure elements with viscous dampers are deduced,and the correctness of the programming in this paper is verified by the comparison of numerical examples.(2)This paper expounds the significance of setting viscous dampers in concrete structures of new buildings and existing buildings respectively,deduces the formula for calculating the additional damping ratio,and compares and analyses the different effects of dampers placed in different positions on the structure according to the structural deformation decomposition.(3)For structures whose deformation meets the requirements of codes,an improved optimization process based on inter-story shear force is proposed in order to achieve the goal of reduction design.Firstly,the significance of reducing the inter-story shear force on saving the amount of structural materials is discussed from the aspects of seismic structural measures and internal forces of components.The influence of seismic grade of structural measures on the amount of materials is analyzed by comparing the design models.Secondly,the influence of inter-story shear on inter-story deformation is discussed.Finally,the optimization function of damper coefficients with the aim of reducing design is proposed,and the process of optimizing damper position and damper coefficients is given.(4)For existing building structures whose deformations do not meet the requirements ofthe code,the optimization method of dampers is proposed in this paper,taking into account the two objectives of inter-story displacement angle and base shear force.For existing buildings,when the inter-story displacement angle exceeds the limit,viscous dampers can be installed to reinforce the existing buildings,but the effect of dampers on the structural base shear should be taken into account at the same time.Firstly,the objective function of the damper's vertical position optimization is proposed.Secondly,according to the different load distribution in the structure,different kinds of structural models are designed.Thirdly,the weight coefficients of the objective function are analyzed for different models.Finally,the optimization function of damping coefficient is proposed,and the method of optimization is given.