Study On Damping Efficiency Of Energy Dissipation Structure With Viscous Damper

Energy dissipating structure can dissipate the energy that seismic input structure through the added energy-dissipating device in main structure,thereby reducing seismic response of the main structure and realizing the seismic fortification target of structure.When the energy dissipation technology was written in "Code for seismic design of buildings"(GB 50011-2001)and "Technical specification for seismic energy dissipation of buildings"(JGJ 297-2013).In addition,the energy dissipation technology was encouraged in "Construction of Seismic regulations(consultation draft)",which indicates that the technology will be widely used in China.However,its design theory and calculation method still need to be further improved.In this context,this paper studies the imminent problem of damping efficiency of energy dissipation structure with viscous dampers.It is intended to provide an important guidance and recommendation for minimizing the cost of structural construction after adding dampers.In this paper,two parameters affecting the damping efficiency are proposed and studied: ratio of support member stiffness of damper to lateral displacement stiffness of structural system—support stiffness coefficient(N),ratio of the maximum displacement of damper to the maximum displacement of floor on which the damper is located—story drifts utilization ratio(?).Firstly,the influence of support member stiffness for energy dissipation efficiency of damper is analyzed in detail.Mechanical models of linear damping system under simple harmonic vibration and random vibration are established after considering N,and the relationship between optimal damping parameters and N are derived.Furthermore,the story drifts utilization ratio is proposed to evaluate the damping efficiency of structure after adding viscous dampers.The main factors,such as,the damper arrangement position and the beam-to-column stiffness ratio for ?,are analyzed in detail,and a calculation formula of ? is derived.Finally,a series of typical experiments and the application of practical engineerings are studied,the importance of damping efficiency is fully verified within design of energy dissipation structure.The main research contents and conclusions are as follows:(1)The method of evaluating energy dissipation efficiency is proposed by using story drifts utilization ratio in frame structure with viscous dampers.The calculation formula of ? is derived with respect to the damper arrangement position and the beam-column stiffness ratio.And the influence of ? on damping efficiency is obtained.(2)A mechanical model of linear damping system considering N is established.The relationship between the optimal damping ratio and the minimum peak of frequency response curve of damping system and N are derived by Laplace transform.And the influence of N on damping efficiency is studied.(3)Based on the fixed-point theory in amplitude-frequency response curve,the calculation formulas of theoretical optimal damping ratio and lowest point of frequency response curve are derived for each damping system.It is of great significance to guide optimal design of energy dissipating structure.According to the requirement of accuracy,N>3,N>4 or N>6 are available,when option is N>6,the optimal damping ratio increment and the minimum peak reduction of damping system are controlled within 10% and 5%,respectively.At this time,the effect of N on the energy consumption efficiency of a damper can be approximately ignored.(4)When the effect of ? on structural damping efficiency is considered.An example of an eight-layer reinforced concrete frame structure is used.It is centered that when the damper is arranged on two layers,at 0.25 when three layers are arranged,and at the side when four layers are arranged.When the additional damping ratio and the damping effect of structure are relatively close,the number of dampers are 16 sets,24 sets,and 32 sets,respectively.It is practical and economical to design damping structure that bases on the method of ?.(5)Through shaking table test of the single degree of freedom systems(15 groups)and the multi-degree of freedom systems(8 groups),the following results are obtained.When the arrangement position of a damper is closer to the middle of a beam span,and the N,the beam-to-column stiffness ratio,the floor lateral stiffness are larger,the ? and additional damping ratio of damping system are larger,and the each response of structure is smaller.When a damper is placed on the side,the ? is only 70%~80% of the central arrangement,the additional damping ratio is also reduced.The single-degree-of-freedom system is reduced by 10%~25%.And the multi-degree-of-freedom system is reduced by 20%~40%.The N has a significant influence on ? and the additional damping ratio.With the increase of N in test,? and additional damping ratio are between 0.21~1.10 and 1.5%~26.6%,respectively.(6)Based on theoretical analysis,numerical simulation,typical test and engineering application,it is obtained that when the N is larger and the ? is higher,the damping efficiency of structure is more obvious.And a recommended value of N and ? two parameters are given.At last,a complete "flow chart of damping structure design method based on damping efficiency" is proposed.It is hoped that this study will provide a guidance and recommendation for optimization design and economic analysis of viscous damping structure in the future.