| Among all kinds of natural disasters,earthquake and wind are two common natural disasters which are constant threats to the safety of building structures.In addition to the design of structures to resist earthquake and wind effects,damping(vibration)control is also an important way to reduce the impact of earthquake and wind vibration.After years of development,for energy dissipation components such as buckling restrained brace(buckling restrained brace,BRB),tuned mass damper(tuned mass damper,TMD),viscoelastic damper,and intelligent damper,related technology is more and more mature and more types of novel energy dissipation damping components are constantly emerging.It is now developing in the direction of the application of new materials,new fabrication technology,new controlling method,facilitate of production,transportation,construction and better energy dissipation and damping reduction ability.As a typical representative of light alloy,magnesium alloy is a kind of high-performance metal material with light weight,high strength and excellent deformability.It has been widely used in biomedical,electronic products,high-speed trains and other fields.In the field of civil engineering,the application of light alloy materials needs to be further developed.Therefore,based on the feasibility study and preliminary application of magnesium alloy BRB in the early stage,this paper makes full use of the characteristics of high strength and excellent deformability of magnesium alloy,and further discusses the feasibility and advantages of using magnesium alloy to replace various kinds of low strength steel in the energy dissipation components to improve the energy dissipation performance of components.In order to reduce structural vibration caused by fluctuation wind and earthquake at the same time,a new type of BRB,TMD member and laminated rubber bearing made of magnesium alloy were proposed,and the damping effect of these components in reducing structural vibration caused by wind and earthquake as well as its influencing factors and rules were studied.The main contents and conclusions of the paper are list as below.(1)Deduced and established the response spectrum of wind load and the mode-decomposition response spectrum method for wind vibration analysis.Based on the theory proposed by Vanmarcke,the relationship between the power spectral density function of the random process and the maximum absolute value of the process is derived.Based on this relation,the theoretical calculation formula of of wind load using the mode-decomposition response spectrum method is derived by using the frequency response function of the single-degree-of-freedom system,and the influencing factors are studied.Then,the response spectrum method of mode decomposition for wind vibration analysis of multi-degree-of-freedom system is derived,and the validity of the method is verified by taking a 32-story high-rise building as an example.Compared with the method of considering the dynamic effect of wind vibration with the wind vibration coefficient in the load code of China,the method of mode decomposition response spectrum of wind vibration analysis proposed in this paper can consider the influence of more modes of structure,so it is more accurate and at the same time simpler than time-history analysis.(2)The essential sample size for wind vibration time history analysis is studied.A single-degree-of-freedom structure,a 32-story high-rise building and a transmission tower are designed respectively,and the corresponding guarantee rate of each sample size under different evaluation precision and evaluation index is analyzed,and essential sample size values of three structural systems are given.For the one-degree-of-freedom system is suggested to use the average value of the analysis results of two groups of time-history curves of wind vibration,for transmission tower structures where the wind load plays a controlling role,it is suggested to use the mean value of the analysis results of five groups of wind vibration time-history curves,for structures controlled by seismic action(such as high-rise buildings),it is recommended to use the mean value of the analysis results of three groups of wind-induced time-history curves.(3)For structures where the wind load plays a controlling role in section design(such as transmission tower structures),the BRB of magnesium alloy and the vibration reduction system of TMD composed of magnesium alloy are proposed,as well as both above methods used together.The results show that when the transmission tower structure is located in the high seismic intensity region,the combination use of BRB and TMD is reasonable to reduce the vibration caused by both wind and earthquake.When the transmission tower structure is in low seismic intensity region,the effect of BRB magnesium alloy is not obvious,but the effect of TMD system composed of magnesium alloy is better.(4)For the structures of which the section design is controlled by earthquake action,such as high-rise building,the collapse of furniture in each floor is put forward as a standard to measure the vibration reduction effect,and the TMD system and BRB composed of magnesium alloy are compared,as well as the vibration reduction effect of the combination of the two combined.At the same time,from the point of view of comfort and safety,the difference between the acceleration and story drift angle is compared to verify the effectiveness of the new technology in reducing the structural vibration under the action of wind and earthquake in high-rise buildings.(5)For the structure(a cliff hotel herein)which is affected by both wind load and earthquake,the technology of magnesium alloy rubber bearing isolation is proposed.By comparing the properties of steel rubber isolation bearing and magnesium alloy rubber isolation bearing,it is found that the magnesium alloy isolation bearing has more stable stiffness.This paper studied the combined application of TMD damping system and magnesium alloy isolation bearing to cliff hotel structure,compared the structural response difference before and after the use of vibration reduction measures from the structural comfort,displacement and component stress,and verifies the effectiveness of TMD damping system and magnesium alloy isolation bearing.The innovations points of the paper are as follows.(1)The theoretical calculation process of wind load response spectrum is derived,and the influencing factors are studied.The mode-decomposition response spectrum method of for wind vibration analysis of multi-degree-of-freedom system is derived,and the effectiveness of the method is verified.The single-degree-of-freedom(SDOF)structure,high-rise building structure and transmission tower structure model are designed,the guarantee rate of each sample combination under different discrimination precision and discrimination index is analyzed,and the recommended sample size of the time history analysis of wind vibration is put forward,which provides a reference for the determination of the sample size in the wind vibration time history of the structure.(2)The magnesium alloy BRB and magnesium alloy TMD damping(vibration)system were put forward,its effectiveness in reducing wind and seismic effects in high-rise buildings and transmission tower structures is verified and its reducing rules are studied,providing theoretical guidance for subsequent structural design.(3)For the sake of structural serviceability,the collapse hazard of the furniture in each floor would be a measure to check the vibration reduction performance of components.(4)A magnesium alloy rubber isolation bearing scheme was proposed and combined with TMD members to form a new damping and isolation system,and its effectiveness in reducing the response of the structure under the action of wind load and earthquake load is verified. |
PDF Full Text Request