Seismic Damage Assessment Of Half-through Concrete Filled Steel Tubular Arch Bridge

Concrete-Filled Steel Tube Arch Bridge has been widely used in long-span bridge engineering,due to its light weight,high strength and good stability.Under the earthquake load,the arch bridge structure and components have damage with different degree.Therefore,it is very important to assess the seismic damage of arch bridges.This article uses the concrete-filled steel tubular arch bridge with a main span of 280 m as the engineering background.A whole bridge's finite element model which was created by the large-scale finite element software of Midas civil,it have nonlinear time history analysis under the three-way ground-motion and study the damage status of concrete-filled steel tube members and bridges.It established the local finite element model of concrete-filled steel tubular arch ribs for static analysis by large-scale general finite element software ANSYS,to study the bond-slip mechanics behaviors of structures concrete filled steel tubes.The specific research results are three viewpoints:1.The damage status of the arch ribs,webs,cross-links,booms,and suspension beams of steel-concrete arch bridges are mostly in good condition under the action of Tianjin Earthquake and Anderson earthquake with a peak acceleration of 0.1g-0.3g.The damage of the edge-span is basically in the state of minor and moderate.Bearing support side span in the arch bridge are more prone to damage.The individual bearings were completely destroyed under the action of the Tianjin earthquake with a peak acceleration of 0.3 g.The damage state of the pile foundation is basically intact and slightly damaged.The damage index of each member of the arch bridge increases with the continuous increase of the peak value of seismic acceleration.The side support is the most serious part of the arch bridge,which need to strengthen its seismic performance.2.From the perspective of overall analysis of CFST arch bridge,the weight coefficient is concluded according to the importance coefficient.A weighted sum of the damage states are various components of the arch bridge.The results show that the damage degree of arch bridge under the action of Tianjin earthquake is more serious than Anderson ground motion.Under the earthquake ground motion of Tianjin with 0.1g-0.3g peak acceleration,the arch bridge is in the range of minor damage and moderate damage.When the acceleration peak value is 0.1g under the action of Anderson ground motion,the damage state of the corresponding arch bridge is basically intact.When acceleration peak under ground motion is 0.2g,the damage state of arch bridge is slightly damaged.When acceleration peak under ground motion is 0.3g,the damage state of arch bridge is moderate damaged.3.This article analyzes the sliding failure properties of the interface of a concrete filled steel tube,and take the most unfavorable state of the load under earthquake to have a static solution with the local model of concrete filled steel tube.The results showed that material stress and shear ring deformation gradually become larger with the increase of seismic acceleration peak.The interface slip value is small and there will be no slip damage between materials.