Research On Mechanical Properties Of Multi-directional Displacement Amplified Low-yield Steel Damper

Earthquake is a kind of natural disaster with sudden and destructive nature,which poses a great threat to the safety of bridge structure.Energy dissipation and damping technology is an effective method to improve the seismic performance.Energy dissipation device can be set in the proper part of the bridge structure to reduce the seismic action of the bridge structure,so as to achieve the purpose of seismic resistance.As one of the energy dissipators,soft steel damper is widely used in the seismic of bridge structures because of its good energy consumption performance,low cost and strong engineering applicability.But the following shortcomings exist in the application of traditional soft steel damper:(1)the energy dissipation capacity of damper can not be fully exerted under the action of small earthquake(2)The energy dissipation direction of damper is single.Based on the above shortcomings,this paper proposes a multidirectional displacement amplification mild steel damper.In order to improve the utilization of energy consuming steel bars,a kind of energy consuming steel bar with full section yield characteristics is designed as the energy dissipation element of damper.The main contents of this paper are as follows(1)A displacement amplified mild steel damper with multi-directional energy dissipation function is proposed.The design parameters and structural principle of each component of the damper are described.The amplification mechanism and installation position of the damper are introduced.(2)A new energy consuming steel bar with full section yield capacity is proposed,and the shape formula is deduced.The initial stiffness formula is derived by the virtual work principle and force method,and the yield displacement and yield force are deduced.The results show that the difference between the results of finite element and the formula is within 10%,which proves the correctness of the formula derivation and the rationality of the establishment of the finite element model.(3)The numerical model of the multi-directional displacement amplification damper is established,and the energy dissipation and stress distribution are analyzed.The results show that the hysteresis curve is full and the shape is shuttle type,and the energy consumption effect is good when the displacement is less than 10 mm.The comparison of the energy dissipation capacity between the damper with displacement amplification function and the damper without displacement amplification is carried out.The results show that the number of steel bars is 8and the arrangement angle is 30 ° The initial stiffness of the damper with the effect of displacement amplification is 1.57 times higher and the energy consumption is 2.15 times higher.(4)Based on the numerical model of multi-directional displacement amplification soft steel damper,the paper studies the number of steel bars,the angle of steel bar arrangement,the combination of steel rod arrangement and the parameters of amplification coefficient.The constitutive model of the damper is proposed.The results show that the more steel bars are,the better their energy dissipation capacity is,and the calculation formula of the number of steel bars to the initial stiffness and yield stiffness of the damper is proposed;The overall trend is that the smaller the arrangement angle is,the stronger the energy dissipation capacity is;"20" is recommended for the arrangement and combination of steel bars °+ ten °” The form of the system;The influence of magnification on the performance of the damper is clarified,and the calculation formula of the initial stiffness of the damper is proposed.