Research On Multi-objective Design Method For Energy Dissipation And Shock Absorption Of Structures Based On Seismic Performance Redundancy

Energy dissipation and shock absorption technology is an important means to improve the seismic performance of building structures.It has the advantages of mature manufacturing technology and convenient installation and construction.Viscoelastic damper belongs to velocity damper,which can provide both stiffness and damping,and can provide damping energy when the structure is subjected to wind load or minor earthquake load.To promote application of viscoelastic damping design,developed many additional damping structure design method of viscoelastic dampers,but the basic are the direct design method based on displacement,requires constant iterative trial,so the development of viscoelastic damping structure direct design method for reducing the actual design work has larger research significance.Therefore,in this paper,the middle and low rise concrete frame structure with significant first-order modal components is taken as the research object,and the parameters determination of additional viscoelastic damper is studied as follows,and relevant results are obtained:Traditional incremental time history analysis requires a lot of computational resources,and there is great uncertainty in the establishment of finite element model and the selection of ground motion.The direct evaluation method of IDA(Incremental Dynamic Analysis)curve proposed in this paper can directly obtain the seismic intensity demand curve of the structure.Its main principle is the inverse process of obtaining the response point of the structure by using the static elastic-plastic method.Compared with the numerical calculation methods such as direct integration method,the direct method in this paper is simple and clear.Time history analysis is not needed to save computing resources,and it has enough accuracy for concrete frame structures which are mainly simulated by rod elements.In this paper,three equivalent single degree of freedom models with different heights and Takeda force-displacement hysteretic curve model are used to consider the whole process of concrete frame structure from cracking to yielding,and several different site vibrations are selected for analysis and verification.The calculation results show that the simplified prediction method in this paper has good accuracy for the single-degree-of-freedom model with different periods,no matter hard or soft soil condition,and can approximate the seismic demand curve of the structureThe actual structural vibration is usually not stationary vibration,and the displacement response of the positive and negative sides is not necessarily the same,so the method of calculating the additional effective damping ratio of the damping structure given in the code may overestimate the seismic capacity of the structure.Based on the assumption that the energy consumed by the positive and negative responses is equal,the asymmetry index R is defined to quantify the difference between the positive and negative displacement responses.The calculation results show that R is about 0.8 in the whole plastic development.Considering the influence of asymmetry,the equivalent effective damping ratio of the elastic-plastic energy dissipation of the main structure can be calculated more accurately.The structure should be equipped with safety reserve and multi-channel seismic defense line in order to reflect that the energy dissipation and seismic absorption structure has better seismic capacity than the traditional seismic structure.In this paper,a multi-objective design method based on redundancy is proposed.By this method,the design parameters of viscoelastic damper can be obtained after one design."Multi-objective" is reflected in that the method in this paper also considers the improvement degree of inter-storey displacement of the structure at the structural performance limit,which improves the deformation capacity of the structure,increases the damping of the structure,and improves the energy dissipation capacity of the structure.It can consider the main structure to enter the plastic state and satisfy the multi-level seismic design.The relationship between redundancy and damper parameters is deduced,and 27multi-particle layer shear multi-particle models with varying stiffness distribution and structural strength are designed to simulate concrete frame structures.Viscoelastic dampers are designed for these 27 models by using the design method in this paper,and a lot of seismic time history analysis is carried out.The calculation results show that the additional viscoelastic damper can improve the discretization of the interlayer displacement response of the structure under ground motion,the interlayer displacement tends to be evenly distributed,and the redundancy of the structure is obviously improved.The redundancy calculation accuracy of most structures meets engineering requirements,and the calculation results are conservative.However,more attention should be paid to the calculation results of structures with weak lower layers,which are dangerous.