Study On The Buildings With High Damping Viscous Dampers

The height records of buildings are constantly updated along with the economic development,increasing urbanization,population growth and land supplies shortages.Due to the increment of buildings' height and application of high strength and light weight materials in the structures,super high-rise buildings with high flexibility are sensitive to wind loads and long period ground motions.Viscous damper is a typical kind of passive control device,which dissipates the wind or seismic energy transferred to the structures.And they are widely applied in civil engineering with the advantage of no stiffness,simple structure,low price and convenient construction.However,high-rise buildings with reinforced-concrete shear walls are likely to reduce the efficiency of dampers.It is due to the fact that the inter-story drift generated under earthquake or wind events cannot produce sufficient deformation in the dampers.In order to solve the above problem,a high damping viscous damper is proposed in the paper.It is with multi-lever mechanism,which can improve the energy dissipation capacity of conventional viscous dampers.The mechanical properties and energy dissipated mechanisms of the high damping viscous dampers are researched by the performance test and shaking table test.And the corresponding mechanical model and the design method of structures with viscous dampers are proposed.This study is expected to provide significant references for the analysis,design and application of high damping viscous dampers.The main contents of this thesis include the following aspects.(1)A high damping viscous damper is proposed in the paper,to improve the energy dissipation capacity of conventional viscous dampers with minor deformations under earthquake events.Its working principle,damping characteristics and mechanical model are introduced.Moreover,the damping force and energy dissipation capacity of the novel damper are studied based on theoretical analysis.In addition,an equivalent energy method is put forward to calculate the dynamic responses of the structure with high damping viscous dampers.(2)A mechanical property contrast test and shaking table contrast test between the high damping viscous damper and conventional viscous damper are conducted.Their mechanical parameters of dynamic stiffness,damping exponent and damping coefficient are acquired.The frequency dependency,displacement correlation and velocity dependency of the above two dampers are researched.What's more,their deformation mechanisms,hysteretic characteristics and energy dissipation capacity are compared.Meanwhile,the impact of two kinds of dampers on structural dynamic characteristics and responses are studied.Finally,the validity of the mechanical model and the correctness of the theoretical analysis on the proposed damper are verified through the comparison between the theoretical values and testing results.(3)According to the mechanical property testing results of the high damping viscous damper,the damping performances of the novel viscous damper are better than conventional viscous damper.On this basis,a high damping viscoelastic damper and its mechanical model are presented.And the related performance tests are carried out.Due to the limited deformation capacity of viscoelastic materials,the high damping viscoelastic damper with a constant amplification ratio perhaps is snapped,when the deformation transferred to the dampers is large.To solve the problem,a displacement amplification device with the variable amplification ratio is given.(4)Due to super high-rise buildings are with low damping and small stiffness,the structural responses under wind loads and long-period ground motions are much greater.To solve the above problem,a method using high damping viscous dampers to reduce the structural responses is proposed.In order to testify the damping capacity of the new damper,the responses of a super high-rise frame-core tube structure and the structure with high damping viscous dampers subjected to wind loads and long-period ground motions are analyzed.(5)The design method of damping structures is complicated in current research.It often needs repeated trial process and costs a lot of time.In order to improve the efficiency of the method applied in the damping structure design,a displacement-based design method for the structure with viscous dampers is proposed.It is based on the principle that the lateral seismic forces should be balanced by the structure and dampers together.By this approach,the primary damper arrangement scheme could be fast obtained.Besides,the scheme can effectively avoid increasing the story shear forces in the floor with dampers.