Research On Structure Design Of Double Block Anti-drop-beam Device Of Bridge Structure

In recent years,Seismic activity is more active in China,More bridge structure damage in the earthquake,how to ensure the bridge engineering in the possibility of earthquake still can be safe and reliable operation,has become one of the problems of engineering are concerned,How to ensure that in the possible earthquake,the bridge engineering is still able to safe and reliable operation,which has become the current engineering industry is extremely concerned about the problem.Seismic block is the main protection of bridge bearing and limiting transverse displacement of main girder,it is also the important structural seismic measures for bridge transverse of earthquake region.The existing bridge transverse seismic block is a single line of defense design,which can not meet the dual requirements of energy consumption and limited displacement in the seismic design.In this paper,considering the problems existing in the seismic design and research of the current bridge structure to the limit stop block of bridge,Based on the existing limit stop,the new bridge transverse seismic structure is designed with the principle of "multi-channel defense,functional separation and step-by-step entry".So that it can limit the lateral displacement of the main beam bridge,but also consume the seismic force,reduce the seismic response of the lower structure of the bridge.This paper mainly completed the following work:(1)Design of a new double block of the seismic structure device.Inner side is a small energy-consuming components,take advantage of the plastic deformation of steel components to dissipate the earthquake;outside rigidity components usually with high stiffness and bearing capacity,Take advantage of its strong stability to limit the main beam relative displacement.Energy-consuming block and rigid components together,can effectively play the function to the seismic shock absorption.(2)The nonlinear time history analysis method is used to study the effects of the stiffness and the initial spacing on the seismic response of a single block in two aspects.It is found that the impact force of the block and the main beam is greatly affected by the collision stiffness,Without considering the collision between the main beam and the retaining block,the seismic response of the bridge structure will be underestimated;The collision force increases first and then decreases with the increase of the collision stiffness,and there is a maximum stiffness value that can lead to the seismic action of the bridge structure;The stronger the stiffness,the greater the ability to stop limit;The initial spacing of the common single block structure has a great influence on the seismic response of the retaining block,and it is difficult to determine the optimal initial spacing.(3)The finite element model of double block structure is established by using Midas-Civil software,Analyzing the seismic performance of the block by comparing with the common block under the same conditions,and the influence of the stiffness of the inner block and the initial spacing on the seismic performance of the double block is studied;It is found that the seismic performance of double block is greatly affected by the stiffness of the inner block and the input seismic wave,a smaller stiffness of the energy-consuming components can only dissipate less seismic action,too large stiffness of the internal block will have a greater impact force with the main beam,affecting the seismic performance of the device.The best internal block stiffness is not uniform under the action of different seismic waves.But in general,the double block structure with the appropriate stiffness nonlinear inner block can effectively reduce the seismic action of the bridge pier bottom.The initial spacing of the inner block has little effect on the seismic performance of the double block under the premise of ensuring enough energy dissipation space.(4)By changing the height of the bridge pier,the influence of the pier height on the seismic resistance of the double block is studied.At the same time,the influence of the initial spacing of the inner block is analyzed.In the case of the same block structure,the higher the pier,the smaller the impact force between the block and the main beam,The change of pier height has little influence on the selection of the initial spacing of the inner block under the premise of ensuring enough energy dissipation space.The amount of displacement of the main beam is less affected by the variation of the pier,The limit function of the double block can ignore the influence of the pier height.