Study On Construction Control And Design Method Of Cable Force For 1-80m Tied Arch Bridge On Baoji-Lanzhou Passenger Dedicated Lines

Tied Arch Bridge consists of tied beam,arch ribs and suspenders.The linear and force of the Tied Arch Bridge could achieved the ideal state by adjusting the cable force.Although some of existing research work has discussed about the cable force optimization of the Tied Arch Bridge,these researches don't take into account the safety of the short suspenders.In the actual safety accidents of Tied Arch Bridge,the short suspenders are first destroyed.The paper which takes the Concrete-filled Steel Tubular Tied Arch Bridge of Baoji-Lanzhou Passenger Dedicated Lines as the research object,aiming at the stress safety of short suspenders,puts forward the optimization thought of cable's equal frequency.The main research contents and achievements are as follows:1.The calculation theories of final cable force and construction cable force have been fully analyzed,and the advantages and disadvantages of these methods are summarized.In Finite Element Analysis Software,the finite element model of the background bridge is established.2.The Tied Arch Bridge's cable force has been calculated by the Rigid Support Beam Method.Under the calculation of the cable force,the stress and deflection of the tied beam meet the requirements,and the short suspenders' force of the arch foot has a sudden change.It can be seen that the cable force calculated by the Rigid Support Beam Method could make the force of tied beam become uniform,but cable force is prone to sudden mutation.3.The cable force has been optimized,applying the design concept of cable's equal strength.After the final cable force has been optimized by optimization thought of cable's equal strength,long suspenders have small cable force,and short suspenders have big cable force.The cable force is roughly equal in value.All cable should be destroyed simultaneously.However,when the cable forces are constant,the short suspender will be in high-frequency vibration state.The force of the short suspender is complex.For these two reasons,short suspender is easily damaged.4.The cable force has been optimized,applying the optimization thought of cable's equal frequency.The relationship between the cable force and the cable length is deduced by the calculation formula of the cable's natural frequency,and the ratio of cable force is equal to the square ratio of cable length.After the final cable force has been optimized by using the relationship between cable force and cable length,long suspenders have big cable force,and short suspenders have small cable force.After optimization,the short suspenders' cable force calculated by the optimization thought of cable's equal frequency is significantly lower than the cable force calculated by the Rigid Support Beam Method and Cable's Equal Strength Method.The optimization method of cable's equal frequency,proposed in this paper,ensures the safety of the short suspenders under the premise of ensuring the safety of the tied beam and arch ribs.5.The construction cable force of Tied Arch Bridge is calculated by Unstressed State Control Method.After the construction phases have been analyzed by Unstressed State Control Method,the bridge state is good coincident with the predetermined bridge state.For the Tied Arch Bridge composed of prefabricated arch and cast-in-place beam,when the unstressed length of cable is controlled,the bridge state analyzed through construction phases is good coincident with the predetermined bridge state.6.The natural frequency of cable is recorded by Frequency Method,and the real cable force is calculated.The difference between real value and theoretical value meet the design requirement.When the cable force is surveyed by using Frequency Method,the data acquisition is convenient and the survey results of cable forces are accurate.At last,this paper summarizes the research work of whole paper and forecasts the future research's directions.