Study On Vibration Reduction Performance Of Steel Frame Structures With Additional Metal Dampers

Energy dissipation and shock absorption systems play an increasingly important role in helping buildings withstand earthquake damage.In recent years,more and more new buildings have used metal dampers.It is increasingly important to study the factors affecting the performance of metal dampers and how to determine the damping of metal dampers in structures.This paper establishes the analysis model of the structure,establishes the reasonable restoring force model,makes elastic-plastic time history analysis of the structure by using Fortran language self-compiled computer program,and compares the displacement response value,velocity response value,acceleration response value and energy response value to analyze the shock absorption performance,and then discusses the parameter setting and the layout mode of the damper.In this paper,a method for allocating the damping of metal dampers is also proposed.The method uses the equivalent linear method to determine the target damping through a single particle system and distribute the damping of metal dampers among multiple particles.The main research process and results are as follows:1.Add a metal damper to the single particle structure by establishing a single particle model transformed from a multi-mass system.The metal damper is changed according to three main parameters of the hysteresis curve skeleton model: the first lateral stiffness 6),the first yielding displacement ,and the yield strength .Comparing the seismic response values of each energy dissipation system and the energy consumption of each part,it is concluded that: Keeping the first yield displacement of the metal damper unchanged,increasing the lateral stiffness 6)and the yield strength can effectively enhance the damping effect of the metal damper.2.Based on the conclusion in 1,the effect of increasing metal damper’s lateral stiffness 6)and yield strength on the period change of the original structure is emphatically studied.Through the change of the period T and the stiffness ratio lambda of the original structure,it is found that with the increase of the stiffness ratio lambda,the displacement of the structure decreases effectively,and its reduction effect will also be affected by the period T of the original structure.With the increase of stiffness ratio lambda,the decreasing trend of displacement reduction rate R becomes slower.Finally,the formulas of the relationship between the period T of the original structure and the stiffness ratio λ are proposed when the target displacement reduction rates are R=0.4,0.5,0.6,0.7 and 0.8,respectively.3.Metal dampers are installed in each layer of the multi-storey structure to make the metal dampers parallel to the original structure The effect of increasing lateral stiffness 6)and yield strength of metal dampers in multi-particle system is studied.The input of metal dampers for 15-storey structures is determined by the ratio of metal dampers to the yield strength of the original structures.The values of setting a are 0.1,0.2,0.3,0.4 and 0.5 times of the yield strength of each layer of the original structure respectively.It is found that when the yield strength multiple of the metal damper is 0.3 times of the yield strength of the original structure,the metal damper is most economical and applicable under the condition of guaranteeing the effect of shock absorption.Through the validation model of 20-storey structure,it is found that the situation is still consistent.4.According to the previous chapter,the additional yield strength multiple of each floor is 0.3 times that of the original structure,and the total yield strength of the additional metal dampers is allocated as the total damping.The allocation conditions are:(1)partition allocation;(2)allocation in the upper floor;(3)allocation in the lower floor;(4)allocation in the whole floor.For each floor distribution mode,three methods are used to allocate the yield strength of the original structure,the displacement of the original structure and the evenly distributed distribution.It is found that for the total amount of specific metal dampers,different floor layout has a significant impact on the vibration reduction effect of metal dampers.The optimum control form tables corresponding to various response values are obtained by synthesizing the allocation forms of metal dampers under different floor allocation conditions and different working conditions.The installation forms and allocation methods of metal dampers corresponding to various seismic response values are given.5 Using conclusion 2,the total amount of metal dampers damped in multi-particle system is obtained by using the index of metal dampers(the ratio of lateral stiffness of metal dampers to that of original structures)determined in single-particle system,and the total amount of metal dampers is allocated according to the conclusion of conclusion 4.The procedure is summarized as a method to determine the damping of metal dampers in multi-layer structures.The elastoplastic time history analysis of the distributed system shows that it is very close to the expected shock absorption effect.