Analysis Of Mechanical Property Of Half-through Single Plane Beam-Arch Combination Bridge

The middle through single arch rib beam arch composite system bridge combines the beam bridge and the arch bridge organically.On the one hand,it overcomes the huge arch end thrust of the traditional arch bridge,on the other hand,it improves the stress condition of the beam bridge.It has the advantages of large span capacity of the arch bridge and strong adaptability of the beam bridge foundation.It is a kind of bridge form with beautiful appearance,reasonable stress and economic cost.However,the application of half through single arch rib arch composite system bridge is rare,and there are still some problems to be further studied:(1)Lateral Tilt StabilityFor the steel-concrete composite system bridge with single arch rib,the arch rib has no support outside the plane,and the lateral stiffness and torsional stiffness of the arch rib are very limited,so the overall roll stability of the structure is increasingly prominent,and becomes an important factor related to the safety performance of the bridge.(2)The force problem of suspender beamThe suspender of the middle through single arch rib arch composite bridge is located in the center of the main beam,which is an important stress structure to transfer the suspender force to the main beam safely and evenly,and is the key part of the control design.(3)Force problem of steel-concrete bonding sectionThe arch rib is of steel structure,the main beam is of prestressed reinforced concrete structure,and the steel-concrete joint section of V structure is the key part of component connection and force transmission,whose design reliability is related to the safety of the whole project.This paper mainly studies the following aspects:(1)According to the construction method of the bridge,MIDAS/CIVIL is used to establish the overall calculation model to verify the stability of the bridge,and the most disadvantageous section is found out,which provides theoretical basis and load boundary conditions for local calculation.(2)Based on the overall calculation results,the spatial stress analysis of the suspender beam,V-frame and steel-concrete composite section of the main girder of the bridge is carried out by using ANSYS,and the stress characteristics and stress distribution of the suspender beam under various loads are obtained.(3)According to the overall calculation results,the strength and stability of the arch ribs are analyzed,and the spatial stress analysis of the main arch ring of the bridge is carried out by using ANSYS.The stress characteristics and stress distribution of the main arch ring under various loads are obtained.(4)Because the bridge is a multiple statically indeterminate structure,and the V-structure,main beam and main arch are all rigid connections,the internal force generated by temperature load(overall temperature load and temperature gradient load)at the above connections is very large,and the internal force generated by temperature in some areas accounts for about 30% of the total internal force.In the design of bridge structure,in order to resist the above loads,a strong prestressed steel tendon is needed,but with the increase of prestressed steel tendon,the relative secondary distance will increase.Therefore,the effect of temperature force,shrinkage and creep can be greatly improved the stress of the structure.According to the characteristics of the structure,the original bridge structure is provided with a fracture joint to analyze the stress of the main beam,V-structure and steel arch rib under the temperature load after the fracture joint is set.