Study On Mechanical Behavior Of Connection Between Concretefilled Steel Tubular Column And Steel Reinforced Concrete Beam In High-speed Railway Station Under Impact Of Train

The concrete-filled steel tube structure is often used in the track-structure columns of modern high-speed railway station.When a train derails and crashes into the structure of the high-speed railway station,it is likely to cause the collapse of the station building,resulting in heavy casualties and property losses.The Beam-column joint is important power transmission hub among the components of the station building.This paper selects the joints of concrete-filled steel tubular column and steel reinforced concrete beam with outer stiffening ring and ring beam joints to carry out the finite element analysis.The influence of internal structure such as inner ring plates and inner diaphragms on the impact resistance of the joint is discussed.The failure modes,the impact force-time history,the internal force of the joints and the adjacent members,and the displacements of the joints are studied with different parameters(impact angle,impact velocity,axial compression ratio,steel tube strength,steel beam and outer ring plate strength).Related conclusions are as follows:1.When the velocity reaches 250km/h,The failure mode of the joints with different internal structural measures is that the structural column is sheared at the outer ring plate,and the influence on the core area of the node beam column is less.Therefore,the reinforcement of the connection mode outside the concrete filled steel tube column node can effectively improve the impact resistance of the joints.2.The influence of internal structure on the impact resistance of the nodes is as follows:(1)the influence of different structural measures on the impact force-time history is very small;(2)the internal structure of the node can effectively reduce the axial force of the column to the upper column and the shear force to the adjacent frame beams;After the failure of the structure column,the inner ring plate,inner diaphragms and the inner rib of the column can effectively transfer the axial force and bending moment in the beam,and the inner ring plate has a remarkable effect on the bending moment in the beam;(3)Different construction measures can effectively reduce the node displacement.3.The impact resistance of nodes under different parameters(impact angle,impactvelocity,axial compression ratio,steel tube strength,steel beam and outer ring plate strength)is as follows:(1)The impact velocity has a significant effect on the failure modes of components and joints.When the impact velocity is 150km/h,the structure column is partially bent at the impact position,and the core area of node is not damaged.When the impact velocity is200km/h,the structural column undergoes local shear failure at the impact position,and the node has no obvious damage.When the velocity reaches 250km/h,the structural column is sheared at the impact position,the bottom of the column,and the bottom outer ring plate.In addition,the concrete at the bottom of the ring beam is also damaged by pulling.At this time,the node is destroyed;(2)the impact force-time history,nodal displacement,axial force and shear force of beam are less affected by different impact angles,but the bending moment of the beam is greatly affected.When the impact angle is 45 degrees,the bending moment of the beam reaches a maximum value;(3)The peak value of the impact force,shear force of the beam,and the displacement of the joints increase with the increase of the impact velocity;The axial force of the column at the core area of the node decreases with the impact velocity increases.(4)The peak value of the impact force,axial force of columns in the joint core,shear force of the beams,and displacement of nodes increase with the increase of the axial compression ratio.(5)The peak value of the impact force increases with the increase of the strength of the steel tube.The axial force of columns in the joint core,shear force of the beam,and the displacement of the joints decrease with the increase of the strength of the steel tube.When the strength increases to 420 MPa,the internal forces and displacement can be significantly reduced.(6)the impact force-time history is less affected by the different strength of the steel beam and the outer ring plate.the axial force and the displacement of the node in the core area decrease with the increase of the strength of the steel beam and outer ring plate.the axial force and shear force of beam increase with the increase of the strength of the steel beam and the outer ring plate.When the strength of the steel beam and outer ring plate is345 MPa,the bending moment of beam reaches a maximum value.4.according to the above analysis,the proposals of node design is proposed.