Study On Damage Control Of Precast Shear Wall Structures Linked By Novel Damped Devices

As an important structural system,precast shear wall structure has made enormous contribution to the building industrialization around the world.Under the premise of ensuring the reliability of the connection and the construction efficiency of the precast structure,research on improving the seismic capability of the whole structure and reducing the plastic damage of the main structure will have great significance.According to the damage control design ideas and the deformation characteristics of the precast shear wall structure,two novel damped devices based on the frictional and the viscoelastic energy dissipation mechanism respectively are developed in this thesis to improve the energy dissipation efficiency of damping materials.Starting with the mechanical properties,the proposed novel damped devices are studied in detail by theory,experiment and numerical simulation.Moreover,a damage-control-based design method for the precast shear wall structure linked by damped devices is proposed.Then,the seismic performance of the prefabricated shear wall structure with damped devices is further evaluated.The main contents of this paper are as follows:(1)Starting from the energy analysis method,a novel connecting mechanism which can amplify the relative deformation between walls is designed based on the deformation characteristics of precast shear wall structure and lever principle By analyzing the relative motion relationship of each member,the magnification principle of the connecting mechanism is revealed.Then,in combination with the friction and the viscoelastic energy dissipation material,two novel damped devices which can improve the energy dissipation efficiency of damping materials are developed,respectively.Meanwhile,the relationship between the energy dissipation efficiency of the proposed damped devices and the key parameters of their members is discussed.After some detailed design and size optimization,refined finite element analysis models are established to verify the mechanical properties and the energy dissipation capacity of the novel damped devices.(2)According to the design scheme for the novel damped devices,the test specimens are processed to study the kinematic properties of the connecting mechanism,the mechanical properties of the friction damped device and the viscoelastic damped device,respectively.Meanwhile,the influence of loading conditions on the performance of the novel damped devices is further analyzed and discussed.The experimental results show that the friction damped device and the viscoelastic damped device have several advantages including sufficient initial in-plane stiffness,strong sensitivity to slight deformation of the precast wall,stable damping force behavior and good energy dissipation capacity.(3)Based on the solid finite element analysis method,simplified finite element models of the friction damped device and the viscoelastic damped device are developed in ABAQUS,respectively.The accuracy of the simplified models is validated by comparing the numerical simulation results with the experimental data.Subsequently,the steel and the concrete constitutive material are improved and written through the UMAT subroutine interface to establish the precast shear wall analysis model.Combined with the analysis model of the damped devices and the precast shear wall,a numerical simulation model for the precast shear wall structure is established.To further illustrate the advantage of the damped devices when considering damage-plasticity control,simulated precast walls and structures with different joints are analyzed.The results show that the damped devices can consume a significant amount of energy to protect the precast wall from damage.It means the novel damped devices will play a great role in reducing the plastic damage for the main structure.(4)According to the rule of energy distribution between the damped device and the precast wall,a damage control based design objective for the precast shear wall structure linked by damped devices is proposed.To achieve this objective,the equation of relationship between damping force provided by the damped device and structural energy is constructed.Afterwards,the design strength value of the damped device under the target bearing capacity can be obtained to maximize the energy dissipation capacity.After discussing the influence of the release length of the wall horizontal constraint and the initial stiffness of the damped device on the energy dissipation efficiency,the damage control based design method for the precast shear wall structure is presented.Furthermore,the energy distributions of the precast shear wall structure linked by damped devices with different strength under different earthquake motions are compared to validate the feasibility of the proposed design method.(5)In order to evaluate the seismic performance of the precast shear wall structure,the damage models of precast walls,precast coupling beams and novel damped devices are established on the material level.Then the seismic vulnerability of precast shear wall structures linked by equivalent cast-in-place,friction damped devices and viscoelastic damped devices are analyzed,respectively.Based on the conclusions,the layout scheme of hybrid joints in the precast shear wall structure is proposed.