Research On The Construction Monitoring Of 128m Tied Arch Bridge And Two Key Technology During Construction Stage

Tied arch bridge as a bridge form of combination structure, it gets a great attention in engineering for its characteristics of low requirements for ground and optimal linear in recent years. During the construction process of tied arch bridge, various conditions of constraints it may meet with, resulting the best construction order can't be applied in the construction process, Thus the involvement of construction monitoring is necessary. This paper mainly research on the construction monitoring, take a railway 128 m tied arch bridge as the background, focus on the ordinary construction monitoring, quantitatively differences between different concrete pouring progress in the arch rib and the adjustment of suspender cable force during construction stage. The monitoring work and two key technical problems above researched clearly or not determines whether the structure can achieve a predetermined state as its goal. the main work and research content is following up:(1) The paper expounds the necessity of the construction monitoring, introduces the theory of the construction monitoring and its development in the domestic and foreign. List the data of stress and displacement during the main construction procedures of the key position, and carries them on the analysis. Mainly control the linear of the girder and arch rib,By giving the construction camber of them, which determines the elevation of the formwork.(2) The theory of finite element modeling is elaborated, introduces the process of the midas/civil finite element modeling of railway 128 m tied arch bridge of CFST. On this basis,introduces and establishes the finite element modeling of concrete asymmetric pouring in the arch rib. And then further simulation analysis, simulates 7 kinds of construction process, they are pouring process of all possible. Analyzes the data of stress and deformation on the main location of the structure as an object, find the quantitative differences between concrete asymmetric and symmetric pouring in the arch rib, compares and analyzes the effect of stress and deformation caused in the position by the seven different kinds of pouring process, to find the optimal procedure of concrete pouring in the arch rib.(3) Calculates the reasonable suspender cable force of the 128 m tied arch bridge based on the rigid support continuous beam method. Removes the suspender in the finite element modeling of the whole bridge in the inverse designed order, then gets the value of the first construction tension of the suspender using the backward method. Test the force value of the first cable tension based on the frequency method. Measures the cable force in the bridge finished stage, compares with the design goal, the difference is obvious,the biggest 21.62%.Therefore, the adjustment of the suspender force is done. The adjustment method is:Calculates the deviation-value between cable force measured and the target, the deviation-value is assumed as the target value of the suspender cable force, then use the backward method again, to calculate the reasonable cable force complementary, then apply the complementary tension value on the corresponding suspender, the order is the design order of suspender tension. After the bracket of the tied beam removed, tests the cable force with frequency method, compares the cable force of bridge finish and the value designed, the deviation-value is general in less than 5%, successfully achieve the goal of adjusting the cable force once that can meet its target and design requirements.In the last, describes the main conclusions of this paper and prospects the research work in the future.