Self-Resetting Friction Energy Dissipation Bracing With Displacement Amplification Function And Its Application In Bridges

Under the action of earthquake,ordinary support is prone to buckling and instability under compression,and can not dissipate seismic energy effectively.Anti-buckling bracing can not only provide stiffness for building structures,but also provide equivalent additional damping.It is not easy to yield under tension and compression,which is an excellent energy dissipation damping element.However,anti-buckling bracing is not sensitive to small deformation,and it is difficult to enter full energy dissipation under low intensity earthquake.Large displacement bracing is sensitive to small deformation and has good energy dissipation capacity,but its lack of resetting capacity will still leave large residual deformation after earthquake.Excessive residual deformation will lead to the collapse of the structure or increase the difficulty of the later repair of the structure.In view of the problem that traditional supports are not sensitive to small deformation and have insufficient energy dissipation capacity,and the response amplification damper lacks reset capacity,a self-resetting friction energy dissipation support（SC-DAFB）with displacement amplification function is proposed based on the working principle of bridge amplification,and the following researches are carried out.（1）Basic structure and working mechanism of SC-DAFB support are elaborated,energy dissipation amplification coefficient of friction system is deduced,and theoretical restoring force model is established.（2）The characteristics of the disc spring and the calculation method of the combined disc spring are introduced.In order to explore the influence of the initial amplification Angle and the reduction ratio of SC-DAFB support on the mechanical properties and effectiveness of the support,three groups of support specimens with different reduction ratios are designed,and two initial amplification angles ofθ₀=45°and 30°are set respectively for each group of specimens to carry out low-cycle reciprocating loading tests.Combined with the experimental results,the important mechanical properties of the support such as hysteretic properties,bearing capacity and residual deformation were discussed.（3）The dynamic time-history analysis of the three-span continuous beam bridge with traditional anti-buckling brace and SC-DAFB brace is carried out.The feasibility and effectiveness of SC-DAFB brace on the lateral damping system of the three-span continuous beam bridge under near-field and far-field earthquakes are analyzed,and the influence of near-field and far-field earthquakes on the energy dissipation and damping of the pier structure of the three-span continuous beam bridge is compared。The results show that the hysteresis curve of SC-DAFB has obvious asymmetric flag type characteristics.Reducing the initial amplification Angle can effectively improve the displacement amplification effect of the supports,and increase the bearing capacity and energy dissipation capacity of the supports exponentially.The theoretical restoring force model is in good agreement with the hysteresis performance of the supports in each loading stage.Under different ground motion intensities,the top displacement of bridge piers supported by SC-DAFB can be effectively controlled,and the residual displacement Angle of bridge piers decreases obviously.When the initial amplifying Angle of the support is reduced,the SC-DAFB support load is effectively increased under the same displacement amplitude,showing obvious response amplifying effect,and the seismic energy dissipated by the support is further increased,effectively improving the seismic performance of the bridge.Compared with far-field earthquake,near-field earthquake has greater response to bridge structure and will bring more serious damage to pier structure.