Seismic Response Analysis Of Single-Span Asymmetric Suspension Bridge And Vibration Control Research

In recent years,suspension bridges have developed rapidly because of their beautiful and unique shape and super-strength spanning ability,especially in my country,many long-span suspension bridges have been built.The terrain in Southwest my country is rather peculiar,with high mountains and deep valleys,most of which are in the shape of a "V",and the terrain has large undulations.Therefore,it is necessary to build some bridges with special structural forms in these places to meet their needs,such as single-tower single-span asymmetrical suspension bridges.Compared with ordinary bridges,this kind of suspension bridge has a larger span space and more complex structural forces,and it is easy to generate a large dynamic response under strong earthquakes or long-period earthquakes,thus affecting the safety of the bridge structure.Therefore,it is very necessary to select the appropriate ground motion and study the dynamic response of the bridge under the earthquake.Taking a single-tower single-span asymmetric suspension bridge as the research background,the bridge model was established based on MIDAS/Civil and Ansys finite element software,and the seismic response of the bridge was studied considering the pilesoil-structure interaction effect and collision effect,and carried out based on Seismic control analysis of suspension bridges with viscous dampers and mild steel dampers.The main content of this article is as follows:(1)Based on the MIDAS/Civil finite element software,the full bridge model of the bridge was established,and the static analysis of the suspension bridge and the bridge state verification were carried out to obtain the initial internal forces of each component.The results showed that their internal forces were all within a reasonable range,which was consistent with the designed bridge small differences.In addition,the dynamic characteristics analysis was carried out,and the first 20 order periods of the suspension bridge and the corresponding mode shapes were obtained.The results showed that the bridge is a long-period flexible structure,and the low-order mode is dominated by the participation of stiffening beams,and the stiffening beams have good Torsional rigidity.(2)Based on the Ansys finite element software to establish a suspension bridge model,select three different seismic waves,adopt the way of one-way input along the bridge direction and across the bridge direction,and carry out multi-point consistent excitation on the suspension bridge,and explore the pile-soil-structure interaction.At the same time,the vertical input is increased,and the seismic response analysis is carried out again.The results show that: the characteristics of the ground motion and the input direction will affect the response results;the multi-directional input of the ground motion,and the interaction of pile-soil-bridge adverse effects on the structure.(3)The impact of the impact of the main approach bridge at the expansion joint on the seismic response of the suspension bridge is explored.By changing the expansion joint gap,the stiffness of the collision unit and the weight of the upper structure of the approach bridge to change the period ratio of the main approach bridge to explore the influence of their changes on the seismic response of the suspension bridge,the results show that: the peak value of the collision force at the gap of the expansion joint,the number of collisions and the stiffening The absolute displacement of the beam shows different changing laws with the change of the parameters;the displacement of the top of the bridge tower and the internal force of the tower bottom are basically not affected by the change of the parameters.(4)The damping control effects of the two damping devices are studied.Viscous dampers and mild steel dampers are selected,and the shock absorption control analysis of the suspension bridge under uniform excitation is carried out under the input of seismic waves with a large seismic response,and the optimal parameters of the two dampers are given through parameter sensitivity analysis,and then The comparative analysis of the damping effects of the two dampers shows that:both damping devices have good damping effects,but the control of the displacement of the mild steel damper is better than that of the viscous damper,while the viscous damper has a better impact on the tower The control of bottom internal force is better than that of mild steel damper.