| The concrete-filled steel tube arch bridges are widely used in engineering practice due to their superior mechanical properties,low cost,fast construction,and easy maintenance.The successful construction of the 1st Yangtze River Bridge in Hejiang solved the key problems in the design and construction of the super-large-span steel-tube concrete arch bridge.With the continuous improvement and innovation of design theory and construction technology,it will become possible to build a 700-meter-class steel-tube concrete arch bridge.According to related research,a 700m-level arch bridge can achieve the spanning capacity of a 1000m-level suspension bridge.At the same time,the construction of an arch bridge in a mountain valley can avoid the super-high pier tower of the cable-stayed bridge.In other words,the concrete-filled steel tube arch bridge is very economical and safe.Therefore,it is necessary to carry out the study of 700m-level arch bridge and apply it to engineering practice as soon as possible.This paper summarizes the development and research progress of large-span concrete-filled steel tube arch bridges at home and abroad,and analyzes the application prospects of 700m-level arch bridges.The rational selection of the arch axis coefficient and the vector-span ratio of the long-span concrete-filled steel tube arch bridge and the structural design of the main arch are analyzed.According to the characteristics of large span and constant load of 700 m concrete-filled steel tube arch bridge,the trial design structure plan of the six tube structure concrete-filled steel tube arch bridge with a span of 700 m is proposed.and analyzed its static performance,stability,power and seismic performance and buckle safety.The specific research contents are as follows:1、Firstly,the static performance of the proposed 700 m concrete-filled steel tube arch bridge is analyzed,and various components of the main arch are checked and calculated according to the current specifications:It shows that its bearing capacity and structural rigidity meet the requirements of the code.2、In the finite element software MSC.MARC,the Python script programming language was used to write the parameterized model of the 700-meter concrete-filled steel tube arch bridge.The value of other parameters is analyzed for the influence of the main arch force,and the reasonable value range of the parameters is obtained.The optimal model parameters were obtained: the arch axis coefficient m = 1.4,the vector span ratio1/4,the arch section height 12 m,the main pipe diameter φ1200×24mm,the arch rib inclination angle is 6° and the lateral connection of the arch rib span is strengthened.3、Based on the above-mentioned arch parameter analysis,a set of reasonable parameters is selected to perform elastic buckling analysis on the span concrete-filled steel tube arch bridge,on the basis of which the geometrical nonlinear effect,material nonlinear effect and double nonlinear effect are calculated Stability safety factor,and the plastic development trend of the arch during loading.The results show that its stability meets the requirements of the specification;the material nonlinear factors have a significant effect on the stability of the arch;the ultimate instability mode of the arch is the overall lateral instability.4、The dynamic characteristics of the concrete-filled steel tube arch bridge are analyzed,and the seismic performance is analyzed by the dynamic time history method.Finally,the division of the arch rib segment,lifting capacity and construction safety of the concrete-filled steel tube arch bridge are analyzed. |
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