Theoretical And Experimental Research On A Curved Steel Damper Used In The Structures

Structural energy dissipation technology as a passive control technology is widely used in new construction, seismic strengthening and repair of the structure after the earthquake because of its efficient, safe and economical characteristics. When experiencing a large earthquake, energy dissipation devices installed in the structure enter the non-elastic state first to provide greater damping, dissipate a large amount of seismic energy and reduce the damage of the main structure and components. Based on the existing research, a novel curved steel damper is presented. The damper has a simple structure, a clear force performance and good stability characteristics. The in-depth and systematic research of mechanical properties of the curved steel damper, the seismic performance of concrete shear walls and the steel frame structure with the dampers and seismic design method for energy dissipation structure is conducted. The main research contents and achievements are as follows:(1) A novel curved steel damper is presented. According to the theoretical knowledge, the formula of the elastic stiffness, yield strength and yield displacement of the damper is given. The influence of various parameters of dampers is analyzed by numerical model. The plate thickness and radius of the circular arc have effect on the elastic stiffness, yield strength and yield displacement. The steel plate width have effect on the elastic stiffness, yield strength but no impact on the yield displacement. According to the stress analysis, the stress distribution of the curved steel damper is the arc-terminal region has more stress and the top circular area has less stress.(2) The experimental research on mechanical properties of curved steel dampers was carried out. After standard loading and fatigue loading, the hysteresis curve of four specimens ware full and no pinching. There were no obvious cracks. During the test, the performance index did not appear significantly decreased. The ductility coefficient and energy dissipation coefficient are larger. These all show that the damper has stable hysteretic behavior, good energy dissipation capacity and nice plastic deformation capacity. Numerical analysis of hysteresis curve with the experimental results can better coincide with test results. And mechanical properties by theoretical analysis can better coincide with the numerical analysis and test results. According to the experimental value, the value of numerical simulation and theoretical calculations to determine the coefficient of formulas can get the complete formula of mechanical properties.(3) The low cyclic loading experimental research on concrete shear wall with curved steel dampers was carried out. A novel concrete shear wall is presented. The ductility and energy dissipation capacity are improved by opening slots in concrete shear wall and putting the dampers in slots. A new type of damping shear specimens DSW and ordinary concrete shear wall specimens SW were produced. The specimens had the same vertical pressure. They were carried out the horizontal force and displacement loading. The cracks of DSW focused on the upper end and bottom of the wall piers. The cracks in the specimen SW were upward from the bottom of the wall and they were shear oblique cracks. The DSW has fuller hysteretic curve, bigger ductility coefficient and energy coefficient. According to the stress analysis, dampers of the DSW are gradually yield. It shows that dampers dissipate a part of the energy. The numerical analysis of the skeleton curve and force characteristics can be consistent with the test results. Therefore, the concrete shear wall with curved steel dampers has better deformation capacity and more stable energy performance.(4) The shaking table experimental research on steel frame with curved steel dampers was carried out. The similitude law of the model is given. The 1:3 scale models were input El-Centro wave, Taft wave and Washington waves. The seismic intensity was 8 degrees (0.3g) frequent earthquake, fortification earthquake, rare earthquake and 9 degrees rare earthquake. The steel frame structure with dampers is named condition 1 and the steel frame structure is named condition 2. Condition 1 has significantly greater frequency than condition 2. With peak acceleration of seismic wave increasing, the frequency of the structure reduces. The trend shows that the stiffness of the dampers has been changed after yielding. The dampers have significant effect on the acceleration and displacement control. With peak acceleration of seismic wave increasing, the area of hysteresis curves is progressively larger to dissipate more seismic energy. The dampers located in the bottom are yield first than in the upper. The numerical analysis by S AP2000 can be consistent with the test results.(5) An adaptive accelerating genetic algorithm for design and calculation of damping structure is presented. It has good convergence effect, small error and fast convergence characteristics by the classical mathematical models testing. Using displacement and acceleration dual objective function, the location optimization of metal dampers can better able to draw the corresponding optimal arrangement. It can reach the full damping effect of dampers. The optimal ranges of yield displacement ratio and stiffness ratio are determined by making the analysis of parameter analysis for energy dissipation structures.(6) The displacement-based seismic design method is studied. Three performance levels for energy dissipation structure which are "good use", "life safety" and "to prevent collapse" are analyzed and determined. The equivalent damping ratio formula for energy dissipation structure with metal dampers is deduced. Taking the eight-story reinforced concrete frame structure for example, the whole process of design was carried out. The dynamic time history analysis has been carried out to verify the results. The results prove that the energy dissipation structure designed by displacement-based seismic design method is safe. Thereby this method is feasible and can realize the expected performance requirements.