Study On The Earthquake Collision Response And Anti-drop Measures Of Beam Bridges

As is known to all, the bridge is a key node in the highway transport network. Sopeople pay more attention to its earthquake and disaster prevention function. Understrong earthquake, as there are differences in dynamic characteristics between bridgespans, or affected by non-uniform ground motions，the upper structure of the beambridges will be prone to large displacement, causing collapse or a collision between thebeams and resulting in paralysis of the entire transport network.This paper combineswith “Study on seismic characteristics of high and low piers and seismicisolation-measures in the mountains by Department of Transportation in YunnanProvince” project, and researches a device that can prevent collapse and collisionsbetween beams. Here is my research work carried out in this paper:①Researched lots of examples related to collapse and collisions of bridgestructures under seismic actions, summarized the status of research issues and ways ofcollapse and collisions between bridges, recalled the proof system specifications in theU.S、Japan and China and explored the advantages and disadvantages of differentkinds of anti-drop devices.②Used the MIDAS CIVIL to set up a basic dynamic model of a40-meter longmulti-span beam bridge and analyzed its seismic response characteristics.③By analyzing, we could find that it’s much easier to have collapse or collisionsin abutments expansion joints than in intermediate expansion joints, tapered high piersthan contour pier expansion joints, and high piers than low piers. What’s more, thegreat collision forces in expansion joints between bridges can’t be ignored and neededto be solved.④Through trial, we developed a collapse-proof device with dampers (undertested). The device can help to prevent or reduce the collisions and collapse betweenbridges by energy dissipation. Even if the dampers are damaged in the earthquake, thecollapse-proof device would also achieve the aim of preventing collapse by dependingon own strength.⑤Explored the effect of the collapse-proof devices: After being set, thecollapse-proof devices could reduce the relative displacement between bridges, preventcollapse and collisions and reduce the relative replacement of the LRB along the bridges. So the shear of the LRB on each bridge span would be smaller and more even,thus protecting the lead-bearing effectively.⑥It’s the most effective to set the collapse-proof devices between the beams andthe piers and it can’t be set in contour piers. It would be better if the collapse-proofdevices are set in higher piers.