Mechanical Properties Of Continuous Beam-Arch Composite Bridge By Arch-Forming Impact Analysis And Programme Comparison

A single beam or arch structure can no longer meet the spanning capacity and aesthetic beauty of large-span bridges.Continuous beam arch bridges have strong spanning capabilities and large structural rigidity.They have the common advantages of continuous beams and steel pipe arches,whether they are railway bridges or highway bridges.is widely used.At present,the span of continuous beam arch bridges is getting larger and larger,and there are many construction methods of arch ribs.Comparative analysis of the stress and deformation of each structure and the choice of arching method for different types of bridge rib construction methods for this type of bridge The guarantee and safety of the system have certain practical significance.In this paper,a(90 + 180 + 90)m long-span railway continuous beam arch bridge is used as the engineering support,and the following studies are mainly carried out:(1)The structural form and characteristics of the continuous beam arch bridge are summarized,and the advantages and disadvantages of several arching methods are described.Use the finite element simulation software Midas/Civil to perform finite element simulation on the overall structure of the bridge under different arching methods,analyze the stress and linear changes of the arch ribs and main beams during the construction process and the operation phase of the bridge,and summarize their stress And linear changes.During the construction of the bracket method,the maximum deflection of the main beam can reach105.5mm;during the construction of the vertical rotation method,the maximum deflection of the main beam is 16.1mm.After the construction is completed,the maximum stress difference between the upper and lower edges of the main beam is 22.5% and 21.1%.In the operation stage,under the condition of temperature load,the vertical deformation of the arch rib has a significant effect on the temperature change.Under the conditions of overall heating and cooling,the maximum vertical displacement of the arch rib is-2.6mm and-21.2mm.(2)Based on the Midas / Civil space finite element model under different arching methods,comparative analysis of the stress characteristics and linear changes of the main beam and arch ribs during the construction stage,and the arching method of the continuous beam arch bridge from this aspect select.The influence of the construction load duration,the demolition method,the counterweight and cable optimization is analyzed.And it is concluded that the increase of mid-span mid-deflection increases with the extension of construction load duration;continuous beam arch bridges should be disassembled from the mid-span to the arch foot during the construction of the bracket method;the longitudinal range of the weight should be set Near the beam end support.(3)Use the bending energy minimum method to analyze the cable force of the bridge.Under the condition of reasonable cable force,the cable force is evenly distributed.Except for the short boom,the cable force value is about 373 kN.The arch rib steel tube is under uniform compression,and the stress of the main beam is-1.5MPa~14.6MPa.It is within the allowable stress range of C55 concrete and the deformation of the main beam is smooth,which meets the requirements of the specifications.The difference method is used to analyze the construction cable force,and its cable force changes smoothly.After the second phase of paving,the cable force reaches a reasonable bridge cable force,and the accuracy meets the requirements.(4)The analytic hierarchy process was used to conduct a comparative study on the arch rib construction scheme of different influencing factors of this continuous beam arch bridge.Through calculations such as judgment matrix,comprehensive matrix and judgment matrix consistency test,it was concluded that the vertical beam method should be selected for this continuous beam arch bridge Arch rib construction.In this paper,through the combination of simulation and actual measurement,the stress and deformation of the main beam and arch rib of the continuous beam arch bridge under different arching methods are analyzed and compared.It has practical reference value for similar arch rib construction in the future.