| With the progress of society and economy,the losses caused by earthquakes areincreasing.Therefore,it is always the focus of civil engineering research to ensure that buildings can continue to exert their functions and reduce the vibration damage of buildings when the earthquake is coming.Because there are lots of old bridges and dangerous bridges which are not considered seismic strengthening in our country,and these bridge play an important role in the transportation.The common seismic isolation device has the limitation of complicated design and installation,difficult maintenance and higher price.Therefore,it is imperative to develop a kind of seismic isolation device with flexible and convenient installation,controllable performance,high energy dissipation efficiency and easy maintenance and reinforcement.High damping rubber and shape memory alloy are two excellent engineering materials with super elastic,high damping and self recovery characteristics.It has a good application prospect in civil engineering.In order to synthesize the superior properties of the two materials,this paper develops a combined damper that high damping rubber winded by SMA wires.In this paper,the tensile properties of superelastic SMA wire,the dynamic and static compression performance of a high damping rubber cylinder,the mechanical properties of the new type combination damper,the theoretical calculation of the static compression stiffness of the restrained rubber isolation,and the energy dissipation and damping system of the new type damper are systematically studied.The main contents are as follows:(1)Experimental study and Analysis on mechanical properties of high damping rubber and Ni Ti SMA wire.High damping rubber can better exert its high damping energy dissipation characteristics under low frequency load conditions.In order to make full use of the super elasticity and high damping performance of Ni Ti SMA,the working strain of SMA wire should be ensured to be2%-8%.(2)Design and experimental study of a combined damper that high damping rubber winded by SMA wires.The Ni Ti shape memory alloy wire with different winding ways can significantly improve the vertical elastic modulus of the high damping rubber.The new combination damper has the advantages of flexible controllability and convenient installation.At the same time,the experimental study shows that the new type of composite damper still has high energy dissipation capacity in high frequency load,and with the decrease of the winding spacing,the secant stiffness and the dissipative energy of the combined damper gradually increase.(3)Analysis of static compression stiffness of rubber dampers with external winding material.Based on the elastic theory and experiment,a theoretical calculation formula for static compression modulus of rubber cylindrical shock absorber with external winding is proposed in this paper.The formula can predict the variation of axial compression modulus with the winding mode.(4)Application of composite damper that high damping rubber winded by SMA wires in seismic energy dissipation control of bridges.The combination damper with high damping rubber and shape memory alloy can effectively increase the seismic capacity of the bridge and make the stress of the bridge member more uniform. |
