Research On Seimic Performance Of Friction Pendulum Isolated Frame Structures

In recent years,seismic isolation technology has been used in more and more buildings.Many countries,such as the United States,Europe and New Zealand,have made regulations for the design method of seismic isolation structure which make the design of seismic isolation structures more and more standardized.In China,the "Code for Seismic Design of Buildings" is the first national standard to formulate regulations for the design of seismic isolated structures,and the recent "Standard for Seismic Design of Buildings" has made more specific requirements for seismic isolation design.However,most of the requirements for isolation structures in Chinese codes are based on rubber isolation,and less consideration is given to the difference between the friction pendulum system and rubber isolation.This thesis compares the two Chinese standards from the perspective of the friction pendulum system.According to the "Code for Seismic Design of Buildings"(GB 50011-2010),a structure with the friction pendulum system and a seismic-designed structure are designed,and scaled models of the two structures are constructed.Shaking table tests are conducted to analyze and summarize the seismic performance of the friction pendulum system.The main works of this thesis are as follows:1.Design requirements for the friction pendulum system in the "Code for Seismic Design of Buildings"(GB 50011-2010)and the "Standard for Seismic Design of Buildings" are introduced and compared.Two friction pendulum systems are designed for the same building according to the two standards,and the design results of the two are compared,such as floor shear,concrete and steel reinforcement,etc.It is found that the requirements in "Standard for Seismic Design of Buildings" increase the safety reserve of the structure with seismic isolation,but also increase material usage.That's because its fortification target is based on moderate earthquake.2.The mechanical performance test of the friction pendulum system is conducted and a numerical model is proposed.Compared with the experimental model,the numerical model is proved to reflect the test results well,except a large deviation when the axial force is small(27k N).3.According to the "Code for Seismic Design of Buildings"(GB 50011-2010),a four-story concrete frame structure with the friction pendulum system and a same concrete frame structure(not designed for isolation)as the upper structure of the seismic isolation structure are designed,and scale models of the two structures are designed and constructed.Shaking table tests of the two structures are conducted.The test results show that:(1)The friction pendulum system can effectively reduce the damage of the structure.When the ground motion with a peak acceleration of 1.792g(more than 9 degrees rare earthquakes)is loaded in three directions,the seismic-designed structure is destroyed,while the structure with the friction pendulum system is slightly damaged and only small pieces of concrete spalled in some areas.(2)After the isolation starts to slide,the interlayer displacement angle of the isolation structure is smaller than that of the seismic-designed structure,and the difference between the two increases with the increase of the peak acceleration.When the peak acceleration reaches 1.11g(9 degrees rare earthquakes),the minimum interlayer displacement angle of the isolation structure is 0.1 times of that of the seismic-designed structure.The acceleration amplification factor of the isolation structure is 0.9 to 0.4 times of that of the seismic-designed structure,and the ratio of the two decreases with the increase of the peak acceleration.(3)The hysteretic curve of the friction pendulum system is full.That shows the friction pendulum system has good energy dissipation capacity and can well protect the upper structure.