Analysis Of Construction Process Of Main Arch Ring Arch Bridges Reinforced With Concrete-Filled Steel Tubes

In the outsourcing concrete construction of arch bridge reinforced with CFST,the first outsourcing concrete pouring process is the most difficult,risky and time-consuming procedure.In this paper,a 200m stiff skeleton concrete arch bridge under construction is taken as the research object.In order to improve the safety of the air concrete pouring process and shorten the construction period,the improved construction technology of hoisting stiff skeleton with the bottom slab is proposed,and the related research on the stress status of main arch in the construction process is carried out.The main research contents and conclusions are as follows:(1)The study on the stress status of the main arch ring in the hoisting process of the stiff skeleton with bottom slab shows that the hoisting construction method with the bottom slab is feasible,the stress of the chord tube is relatively safe in the construction process,and the concrete tensile stress level of the bottom slab is high,which has certain risks(2)In view of the problem that the tensile stress level of the concrete bottom surface of the front section of precast bottom slab at each section is relatively large when the stiff skeleton section with bottom slab is hoisted by the double-buckle method,it is proposed to use the three-point method to hoist the arch ring segment The force condition of the arch ring under the action of three buckle points is analyzed.The results show that when the three-point method is applied,the inner and outer upper strings are more even and reasonable,and the maximum tensile stress of the concrete bottom surface of each section is obviously improved.(3)The subsequent outcast concrete pouring process with the stiffener of the bottom plate is studied.The difference between the arch ring structure stress and the arch top deflection when the multi-face synchronous casting method and the single working face casting method are used in the web casting process are compared and analyzed.The results show that the tensile stress of the concrete in the chord tube of the vault and skewback section will exceed the specification limit by the single working face casting method with the working face lto3 from the vault to the skewback.According to the influence line of the deflection of the arch and the influence line of the stress on the arch of the arch,the casting process of the single working face is optimized.After the optimization,the stress state of the arch ring structure is good,all meet the requirements of the specification,and the deformation of the arch ring is uniform and reasonable.(4)The stress state of the main arch ring in the bridge stage is studied,and the bending stress state of the key section of the arch ring is compared and analyzed.The results show that the stress of each member of the main arch ring meets the requirements of the code,and the ideal bending stress can be obtained by means of multi-point balanced pouring method in the construction of external concrete with bottom slab.