The Earthquake Damage Control Of RC Frame-shear Wall Structures By Energy-Dissipative Coupling Beams

Frame-shear wall structures are one of the most widely used structures in China as the residential or office buildings. They have dual aseismic systems, namely, the shear wall and the frame. When being caught by a huge earthquake, the coupling beams in the shear wall yield first, which consume a lot of seismic energy. The design philosophy is to protect the main vertical structural members such as coloumns and shear walls by sacrificing the horizontal structural members such as the coupling beam. Therefore, the coupling beams are commonly designed with sufficient lateral reinforcement to provide a large ductility and a large energy dissipation capacity. However, once the coupling beams fall into damage, they are very difficult to be repaired. Even though the vertical structural members are well protected, the building has to be demolished eventually. Combining an energy-dissipative device with the coupling beam, called energy-dissipative coupling beam hereafter, is one of the effective options to improve the seismic performance of frame-shear wall structures. They provide a new method for reducing walls’ damage, recovering structures’ function quickly after an earthquake and reducing the cost of post-disaster reconstruction. However, at present the research of the frame- shear wall structure with energy dissipative coupling beams is still limited, and the control effect remains to be confirmed. This study experimentally and analytically examines this structure system, systematically covering the energy-dissipative devices, the coupling beams combined with the dampers, substructure hybrid testing, nonlinear time history analysis and a design method based on the continuous theory. The main achievements of this dissertation are as follows:1. Experimental research is conducted on the mechanical performance of the steel damper with slits. Through the low-cycle quasi-static test, the steel dampers with different slit patterns are examined in terms of the ductility, the over-strength ratio, and the energy dissipation capacity. Dampers with slit width of 2mm are simulated through the sophisticated finite element analyses. The damage model and the value of the damage parameters are discussed. By macroscopic Bouc-Wen model, dampers with slit width of 6mm are simulated. The relationship between shape control parameters of Bouc-Wen model and mechanical properties of dampers are established by regression analysis.2. The comparison experiment is conducted on a traditional coupling beam and the energy-dissipative coupling beams. The advantages of energy dissipation coupling beam in terms of the damage control on the coupling beam and walls, the energy dissipation capacity, and the deformation capacity are verified. The effect of the over-strength ratio on the energy dissipation coupling beam is studied as well.3. The large-scale substructure online hybrid test is conducted on a traditional shear wall and a shear wall with energy-dissipative coupling beams, respectively. Based on a prototype structure of 18 floors, the bottom six stories are taken out and scaled to 1/3 as the experimental substructures, while the rest simulated numerically by ABAQUS. After three rounds of hybrid testing with different earthquake levels, the quasi-static test was conducted to examine the failure pattern of the overall specimen. The control effect on the storey drift and seismic force are verified, meanwhile the deformation demands of energy-dissipative coupling beams is measured.4. The parameter analysis of frame-shear wall structures with energy-dissipative coupling beams is conducted. By using finite element software Marc, the parameter analyses are performed. Three models with different heights, i.e., 10, 20, and 30 stories, are examined. The major design parameters, such as the the span ratio, the stiffness and the strength of the energy dissipation coupling beam, are investigated through nonlinear time history analyses. The storey drift, storey shear force distribution and the energy dissipation distribution along the height are examined. The reasonable range of the design parameters is proposed.5. A seismic anlysis method of the frame-shear wall structure with energy-dissipative coupling beams is proposed based on the equivalent elastic continuum method. It combines the continuum method of the traditional coupled wall and the MPA method while considering the design parmaters of energy dissipative coupling beams. The plastic capacity of energy-dissipative coupling beams and walls are taken into consideration, and the period the vibration modes and the additional damping ratio of the structure are calculated. The equivalent elastic continuous method is put forward with MPA method, which can be used for the deisgn and optimization of dampers.