| Concrete-filled steel tubular arch bridge has good mechanical characteristics and high bearing capacity,so it is more and more used in bridge construction.The concrete-filled steel tube arch bridge is a ternary structure composed of arch ribs,tie beams and suspenders.Due to the influence of construction deviation,the alignment and internal force of the bridge state are inconsistent with the design.Therefore,monitoring and control of bridge construction is the key to high-precision construction.As a force transmission component,the suspender plays a key role in ensuring the safety of the structure.However,in actual operation,the short suspender will be damaged first.Therefore,it is very important to optimize the suspender force and suspender tension sequence.Based on the engineering background of 140 m Nielsen system across Huiyan Expressway Bridge on Guangshan Railway,this paper mainly carries out the following work :(1)Based on the design drawings,combined with the actual construction sequence,the finite element analysis software Midas / Civil was used to establish a three-dimensional model of a 140 m concrete-filled steel tube arch bridge.By simulating the key construction stage,the deformation and cable force of each stage are compared with the design value,and the correctness of the simulation is verified.The simulation data is used to guide the construction stage and predict the construction of the next stage,which provides guidance for bridge construction.(2)In the process of bridge construction,the alignment,stress and cable force of the bridge are monitored.According to the simulated results,the actual construction process is controlled,and the measured values are compared with the theoretical values.The influence of each parameter on the stress and alignment of the arch rib is studied by setting the parameters of the three main parameters affecting the construction control,such as structural stiffness,arch rib concrete density and temperature.Through analysis,it can be seen that the height difference of the symmetry point after the closure of the arch rib is within 1 mm,and the height difference between the middle spans of the east and west arch ribs is within 3 mm during the second phase of construction,which meets the requirements of the specification.The adjusted suspender cable force is within 5 %,which meets the design requirements.The traditional density detection support device is studied.The device needs the staff to hold the support device to keep the device stable during the detection process.Therefore,a compactness detection device with roller brake is designed,which solves the problem that the staff ’s hand support device is needed to maintain the stability of the device during the detection process.(3)Based on the theory of cable force optimization for cable-stayed bridges,an overview of cable force optimization for suspension rods is presented.The rigid supported continuous beam method,zero displacement method,and minimum bending energy method are combined with Midas/Civil software to solve the cable force of completed suspension rods.By comparing and analyzing the results,it can be concluded that the minimum bending energy method calculates a more uniform suspension force than the first two,but there is still a phenomenon of short suspension force being too large.Optimize the initial calculated suspension rod force based on the equal frequency method and the unknown load coefficient method.By incorporating the optimized suspension force into the model solution,it can be concluded that the unknown load coefficient method calculates a more balanced suspension force and a more reasonable distribution of bending moments.Therefore,the optimization result of the unknown load coefficient method is used as the reasonable suspension force for the completed bridge.(4)Analyzed the stability of the completed bridge structure under different tensioning sequences and the stability during the internal force construction stage.When the beam ends are symmetrically jumped and tensioned in batches after the middle span,the stress and bending moment of the tie beam and arch rib are more reasonable,and the safety and stability coefficient during the bridge completion and construction stages is higher.This not only ensures the reasonable stress distribution of the structure,but also achieves the optimization goal.Therefore,it is determined to perform symmetrical jump tensioning in batches at the mid span and then at the beam end as the suspension rod tensioning sequence. |
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