Study On Dynamic Loading Experiment And Restoring Force Model Of Steel Structure Joints With Added Viscous Dampers In Archaized Buildings

Steel archaized building,which combines modern building materials and construction technology with the characteristics of ancient buildings,is a unique architectural form of China.It not only inherits the traditional Chinese culture,but also has far-reaching significance in the protection and heritage of Chinese ancient buildings.But research shows that steel frame with welded beam-column joints has poor seismic behavior,it’s easy to experience brittle fractures during the earthquake.In order to improve the seismic behavior of the steel structure joint,a new form of the beam-column joint with viscous damper is put forward in this paper,which combines modern energy dissipation technology with the characteristics of archaized buildings.This form of joint with viscous damper will provide the reference for further study of vibration reduction in archaized buildings in the future.Through the dynamic loading test on 4 models of steel structure joint with viscous damper in archaized buildings and 2 models of the traditional joint without viscous damper,the seismic behavior of the steel structure joints with added viscous dampers in archaized buildings were analysed in this paper.The stress characteristic,failure mode and restoring force characteristics such as hysteretic curve,skeleton curve,degeneration of strength and rigidity,ductility and energy dissipation capacity of each joint are obtained from the experimental results.The research results are as follows: Compared with the failure mode of the weld crack in the traditional joint sample,the failure mode of the steel structure joint sample with viscous damper is changed into the material cracking of the plastic hinge zone at the end of the beam.The hysteresis loop of each joint is in a plump-shape,and the displacement ductility ratio is between 1.77 and 2.05.Compared with the traditional joint sample,the ultimate load of steel structure joint sample with viscous damper is increased for 18%~46%.Equivalent viscous damping coefficients of the steel structure joint sample with viscous damper is 1.06~1.67 times of the traditional joint sample when the failure load is reached.The strength and stiffness of each joint sample degenerated obviously when the ultimate load is reached,and the trend is accelerated in general.According to the test data of the beam-column joint with viscous damper under the dynamic loading,a trilinear restoring force model,which consider the stiffness degradation is established by using test fitting method in this paper.First,fitted the test data by software Origin8.5,and then established the trilinear dimensionless skeleton curves model of the steel structure joint under dynamic loading.On the basis of before,the stiffness degradation laws were proposed through further fitting analysis of the test data.Finally,the restoring force model of steel structure joint with viscous damper under dynamic load was proposed with combination of the skeleton curves model,the stiffness degradation laws and the hysteretic rules.Comparison results show that the skeleton curve model of each model which calculated based on the restoring force model fitts better with the measured skeleton curves through the test.The load-displacement relationship of steel structure joint with viscous damper under dynamic load can be preferably reflected by this restoring force model.Also,this model can be reference for elastic-plastic seismic response analysis of the steel structure joint with viscous damper and and the steel archaized building.