Research On Construction Control Key Technology Of Long Segmentalized Continuous Girder Arch Composite Bridge

With the development of science and technology and social progress,the requirements for bridge construction technology are becoming higher and higher.Continuous beam arch composite bridge combines the mechanical performance advantages of arch and continuous beam together reasonably,which greatly improves the mechanical performance and applicability,and is widely used in high-speed railway.Taking a(76+160+76)m continuous beam arch composite bridge as the engineering background,this paper studies and analyzes the key technology of construction control of long-span continuous beam concrete-filled steel tubular arch composite bridge.The main work and research contents of this paper are as follows:(1)The mechanical performance and main advantages of continuous beam arch composite bridge are summarized.The research status of its key construction technology and the shortcomings of existing research are summarized,and the research content of this paper is determined.(2)The finite element model of the whole bridge is established through midas/civil,and the theoretical data of internal force,stress and deformation of each control section in the construction process are calculated.Combined with the field measured results,the comparison and analysis are carried out.Finally,the linear error of continuous beam section is controlled within 10 mm,and the linear error of arch rib is controlled within5mm;In the construction process,the continuous beam and arch rib are in the overall compression state,indicating that the construction control effect is good.(3)This paper expounds the current basic methods of identifying and adjusting the internal force of the suspender,calculates and analyzes the situation that the cable force of the whole bridge is too large after the bridge deck system is paved,compares and analyzes the advantages and disadvantages of the single wheel cable adjustment scheme and the multi wheel cable adjustment scheme by using the influence matrix method and the positive installation difference iteration method,and comes to the conclusion that the difference between the suspender cable force and the ideal cable force can be controlled within 5% through the multi wheel cable adjustment,and the force on the main beam and arch rib is safe in the process of cable adjustment,It has little influence on the alignment of the main beam and arch rib,and this method can be used for reference for similar projects.(4)The local model of arch foot is established by ANSYS,and the stress distribution and change law of arch foot during construction are analyzed.It is found that during the construction period,the arch seat is basically under pressure,but it is easy to produce large stress concentration at the junction of the arch seat and the main beam,and some of the stress exceeds the design strength of C55 concrete.It is suggested to strengthen the reinforcement structural measures here and set a certain concrete relaxation section to reduce the stress concentration phenomenon;The tensile stress at the arch foot increases with the increasing vertical load of the arch rib.Under the conditions of bridge deck laying and secondary tension of the suspender,the tensile stress at the arch foot exceeds the design strength of the concrete.It is suggested that attention should be paid to controlling the load value of the bridge deck system and the tension of the suspender in the construction process to reduce the vertical load of the arch rib;The arch rib steel has a large stress reserve during the whole construction process,which meets the steel strength requirements.By comparing and analyzing with the field measurement,it is found that the measured results have the same law with the finite element simulation results,which shows that the finite element simulation method is reliable and can be used for checking design.(5)The construction technology of the temporary pier of the bridge is introduced,and the finite element model of the bridge is established by using midas/civil.It is concluded that the main beam and the temporary pier are under pressure as a whole in the process of beam transportation.Combined with the measured values,a comparative analysis is carried out to verify the reliability of the calculation of the finite element model.It is proved that when the tied arch stress system of the long-span continuous beam concrete-filled steel tubular arch composite bridge is not completed,the method of establishing temporary piers can effectively improve the stress of the main beam,and the continuous beam can be put into use in advance when the beam is transported,so as to save the construction cost and shorten the construction period.