| With the continuous construction of transport infrastructure in China,the conditions for bridge construction are more complex,requiring crossing deep mountains,canyons or rivers,and the bridge span is increasing.Concrete arch bridges have been built around the world due to their advantages such as large span capacity,diverse construction methods,and low maintenance costs.The Xining River Bridge in Sichuan and the Tian’e Longtan Grand Bridge under construction have spans of 470 m and 600 m respectively.In the design of super long span concrete arch bridges,the structural form of the arch building and the stability of the high columns have become key factors affecting the development of super long span concrete arch bridges.Based on the engineering background of a 600 m super large bridge,this thesis studies the architectural form on the arch of a 600 m span concrete arch bridge and its influence on the structure of the main arch.The main research work is as follows:(1)On the basis of summarizing the architectural structure forms on the arch of concrete arch Bridges with long span and extra long span at home and abroad,this paper studies the cross section forms and span layout of the bridge beams based on a 600 m extra large bridge,and proposes different design schemes for the concrete bridge system and steel-mixed composite structure bridge beams.The influence of different materials,structural forms and span layout on the force of arch ring is compared and analyzed under the optimization of arch axis coefficient,and the bridge beams with reasonable force is selected.(2)Aiming at the stability problem of tall columns of long-span up-bearing concrete arch bridge,four kinds of arch construction layout methods,namely,T-frame continuous beam system,rigid continuous beam system,continuous rigid frame system and main and secondary arch system,are proposed to solve the problem of tall columns.Three structural forms of variable section columns,double-column columns and equal section columns are designed.Based on the minimum eccentricity,the reasonable arch axis coefficients corresponding to the three design schemes are calculated respectively.On this basis,the static characteristics,stiffness and stability are compared,in order to obtain the optimal form of the column.(3)In view of the traditional design method of variable height may arch foot section of negative bending moment is big problems,put forward a new calculation of arch ring formula-cosine curve formula of variable cross-section height.Compared according to the design method,li’s formula and cosine curve formula of the arch ring of sectional height,analysis of arch ring height change on the arch ring static,dynamic and stability,the influence of validation arch ring cross section in the cosine formula proposed in this paper the rationality of variable height.(4)Based on the variable section height of arch ring calculated by cosine curve formula and the proposed arch arch building form,the static,stiffness and stability differences between the arch bridge and the original design are compared and analyzed based on the optimized arch axis coefficient of the concrete arch bridge.Combined with the checking results of the arch bridge bearing capacity,the rationality of the proposed arch arch building form in the 600m-span concrete arch bridge is further verified. |
