Research On Construction Control Of Steel Box Tide Arch Bridge Under Unstressed State Method

The determination of a reasonable bridge state and a reasonable construction state are very important contents for the phased construction of the bridge structure.In order to determine the reasonable construction status of bridges,inversion-installation iteration and erection iteration are generally adopted.These two methods are seriously affected by the temporary load on the construction site.In the case of the under-supported beam arch combination system with an inner statically indeterminate structure,subsequent adjustment of the boom is a tedious process.The steel box tied arch bridge is used here as a background,and the unstressed state method is used to study the stress-free assembly of arch ribs and the reasonable construction state of the suspenders in the entire bridge construction process.The full text is divided into the following four parts in terms of structure and content:(1)Briefly introduce the structure of arch bridges,emphasize the importance of reasonable construction conditions of arch bridges to the state of bridge formation,and lead to the necessity of bridge construction control;Describe the development history,content and methods of bridge construction control;Explain the current research status of the unstressed state method,and point out that the unstressed state method has not been involved in the theoretical calculation of the steel box tied arch bridge;The complexity of the assembly process of the arch rib assembly and the boom adjustment process at the present stage is to explain the necessity and importance of this study.(2)According to the phased bridge equilibrium equation,this paper discusses the conditions for the phased construction of the phased construction and the internal force and the line shape are uniquely determined,which leads to the first basic principle of the unstressed state method and uses two End-consolidation beam to prove;The second principle of the unstressed state method is explained by combining the single-span tie-bar arch bridge in two states with the mathematical theory;Taking a cross-steel box tied arch bridge as an example,the comparison between a completed bridge state and a suspender with a no-stress length in stages was performed to verify the practicability and effectiveness of the stress-free state method.(3)Discusses the concepts and their interrelationships of the construction of arch ribs in stages;Based on the example bridge,a staged assembly model of arch ribs was established,and a stress-free linear flow chart of the arch ribs was established;The tangent initial displacement method was used to obtain the theoretically unstressed line shape and theoretical installation line shape of the arch ribs;The accuracy of this method is demonstrated by comparing the calculated arch rib elevation with the measured elevation.(4)Introduce the method and principle of determining the reasonable construction status of the bridge,and calculate the reasonable construction status of the steel box tied arch bridge by using the inverted-installation iteration method,the erection iteration method and the unstressed state method;A comparative analysis of these methods achieves a reasonable bridge state process by controlling different parameters,and these methods can converge on the nature of convergence;Finally,the actual bridge boom force and the vertical displacement of the main girder are compared with the calculated values to verify that this method can accurately guide the actual construction.In general,using the stress-free state method to calculate the internal force of the steel box tied arch bridge can be well controlled to guide the actual construction process more accurately.This paper supplements the calculation theory of the stress-free state method in the steel box tied arch bridge and provides a reference for similar bridge structure calculations.