Analysis On Static Bearing Capacity And Stability Of Steel Box Arch Bridge In Heavy-haul Railway

The deck type steel box arch bridge structure is light in weight,so it can effectively improve the spanning capacity of the deck type arch bridge and reduce the load-bearing capacity requirements of the foundation.With the continuous research and development of new materials and construction technologies,deck type steel box arch bridges have gradually played an increasingly important role in the construction of railway bridges.Deck steel box arch bridges have many static indeterminate times,many boundary constraints,and complex forces.Therefore,it is meaningful to study the influence of its design parameters on the static bearing capacity and overall stability of the bridge.This thesis takes a heavy-duty railway deck steel box arch bridge as the research background,the author uses Midas/civil to establish a finite element calculation model and analyzes the static bearing capacity and stability of the steel box arch bridge,and then analyzes the Ride-span ratio by changing the design characteristic parameters,number of columns and number of transverse braces on the bearing capacity and stability of steel box arch bridge.Finally,using the finite element software Ansys to do a local stress analysis on the joint between the arch abutment and the arch seat with complex forces,and considering the influence of the welding residual stress on the joint between the arch seat and the arch rib,and draw the following conclusions:(1)Through the analysis of the static bearing capacity of the heavy-duty railway steel box arch bridge,it can be seen that under different load conditions,the stress at the arch foot is the largest,and the maximum stress is less than the design strength requirement of the steel box arch rib material;The maximum displacement value of deck steel box arch bridge appears at the position of the vault,and the maximum displacement value fulfils the specification allowable value of steel box arch bridge.(2)As the ride-span ratio decreases,the compressive stresses of steel box arch ribs under various working conditions increase a lot.The displacement of the crown of the heavy-duty railway steel box arch bridge and the displacement of the bridge deck in the middle of the span also increase a lot with the decrease of the rise-span ratio.(3)Under fulfiling the force requirements of the carriageway slab,the number of columns has little effect on the static characteristics of the bridge structure.The mid-span displacement of the steel box arch bridge and the compressive stress of the arch ribs both decrease in a small range as the number of columns increases less.However,due to the increase in the number of uprights and the weight of the bridge,the number of uprights should be designed reasonably.(4)Under various load combinations,the buckling mode characteristics of each order of the structure are all lateral instability failures of the steel box arch ribs,indicating that the vertical rigidity of the structure is greater than the lateral rigidity of the structure.In addition,the stability safety factor of each buckling mode of the structure is greater than the required value,so the overall stability of the bridge fulfils the requirements.(5)With the decrease of the ride-span ratio,the stability safety factor of each buckling mode is also decreasing,and the decrease of the low-order mode is greater than the decrease of the high-order mode,but the buckling mode of each order the state characteristics are the same.(6)The change of the number of transverse supports has a great influence on the stability safety factor in the first order mode of the structure,which shows that the number of transverse supports plays a crucial role in the overall stability of the structure.The calculation shows that the more the number of transverse supports,the greater the stability safety of the structure.The appropriate number of horizontal supports shall be designed.(7)The change of the number of columns has little impact on the stability safety factor of the low-order buckling mode of the structure.The calculation shows that the more the number of columns,the greater the stability safety factor of the structure.The appropriate number of columns shall be designed.(8)Without considering the welding residual stress,under the most unfavorable load combination,the maximum tensile stress of the steel box arch rib appears at the junction of the arch rib and the arch seat,and the steel box stress and the strength of the prestressed steel bar meet the requirements,and the concrete arch Most areas of the abutment are under compression,the stress contour changes relatively smoothly,and the maximum compressive stress appears on the inner side of the bottom of the arch abutment.(9)The maximum principal stress of the steel box after considering the welding residual stress is mainly distributed at the welding seam.The part of the steel box embedded in the concrete block and the welding seam has a larger tensile stress,and the tensile stress far away from the welding seam is higher.The maximum principal tensile stress is 206.635 MPa,which is an increase of 6.7% compared to the maximum principal stress without considering the welding residual stress.