Reasonable Bridge State Of Reinforced Concrete Tied Arch Bridge And Optimization Of Cable Force Of Suspension

For the down-supported reinforced concrete tie-arch bridge,the boom is a very important tension member for transmitting force.Whether the cable force of the boom is reasonable or not has a great influence on the internal force state and the linear state of the bridge.If it is unreasonable,it will shorten the use of the bridge.Therefore,how to determine the cable force of the bridge boom and the cable force of the construction boom of the tied arch bridge,how can the actual state and the target state be fitted in the construction stage,and some parameters occur during the design-construction and operation and maintenance process.Whether the change affects the safety of the bridge structure.Based on a bridge,this paper studies the reasonable cable-stayed cable force of the tied arch bridge,the reasonable construction of the cable force,the control analysis of the construction stage and the analysis of the influence of certain parameters on the bridge structure.The main research contents are as follows:(1)Firstly,the finite element model of the bridge is established.The four methods of rigid support continuous beam method,rigid suspension method,zero displacement method and bending energy method are used to determine the cable force value of the suspension under reasonable bridge conditions.Under the method,the stress state of the bridge is summarized,and the advantages and disadvantages of the four methods are summarized.At the same time,the cable force of the suspended bridge is optimized.For the rigid support continuous beam method,rigid suspension method,zero displacement method,the cable force is not much difference,the cable force is relatively uniform,the essence of the method is the same,and the bending energy method is used to control the minimum of the arch rib beam.The bending force can be reasonable and uniform for the target,and the method is simple.The resulting cable force value provides a target value for the boom after the construction phase is stretched.(2)Secondly,for the determination of the cable force value of the boom during the reasonable construction stage,the paper adopts the formal installation iterative method,the backward analysis method,the backward analysis-the formal assembly iterative synthesis method and the non-stress state analysis method to aim at the reasonable bridging state obtained in the above section.Solve the cable force value of reasonable construction boom,sum up the advantages and disadvantages of these methods: For the use of dressing iteration,the method principle is simple and clear,suitable for most bridges,can consider the shrinkage and creep of concrete and the sag of the boom Effect,but the result of one calculation has a large deviation from the target value,which requires multiple iterations and a large workload.To the demolition-dressing iteration method,we first propose a set of relatively close initial cable forces for iterative calculation,which effectively reduces the number of iterations.The stress-free state method is consistent with the results obtained by different tensioning schemes as long as the stress-free length and the stress-free curvature are unchanged.At the same time,the stress state of the bridge structure under the three tensioning schemes is compared and analyzed by the unstressed state method.The structure isanalyzed when the 1/4 and 3/4 of the arch ribs of the scheme 3 are respectively pulled to the middle and the end.The internal force is in an optimal state.(3)For the construction control of bridges,this paper mainly monitors concrete hydration heat,bracket deformation and bearing capacity,boom cable force,arch rib and tie beam stress and line shape to ensure the safe construction of the bridge.Through the above calculation,the hydration heat control value,the deformation value of the bracket,the initial tensile force of the boom and the theoretical value of the final boom force after the pavement is completed,and the arch rib and the tie beam of each stage of the boom tension can be obtained.Stress and deformation values.And draw the following conclusions:The hydration heat control is mainly the temperature record mainly including: the temperature of the inlet and outlet;the temperature of the concrete internal temperature sensor;the atmospheric temperature;the temperature of the concrete surface,so the construction stage should be strictly controlled.For the control of the bracket,it mainly includes eliminating the elastic deformation to adjust the elevation of the vertical mold,and at the same time ensuring sufficient support of the bracket.The control of the cable force,stress and line shape of the boom is mainly for the theoretical control value of the key construction stage.During the construction,it is necessary to pay attention to the comparison between the measured value and the theoretical value,and if there is any deviation,adjust it in time.We can apply the theoretical calculations to the practice and guide the construction of the bridge.At the same time,we hope to provide technical reference for the construction of the same type of bridge.(4)Factors such as design choices,construction errors,or bridge damage due to bridge operation.This chapter mainly investigates the influence of parameters such as arch rib stiffness,cross bracing type,arch rib roll,self-weight error,boom stiffness reduction and boom damage on the internal force of bridge structure,and draws the following conclusions:For the stiffness of the arch rib and the characteristics of the material and the size of the section,the selection of different materials and sections in the design stage has a great influence on the stress of the arch rib,the natural frequency and the stability of the bridge,but has no effect on the boom.The type of cross bracing is different,and the stiffness is different in nature.The buckling coefficient and natural frequency of the bridge are sensitive to the change of the cross bracing,and have little influence on the stress of the arch rib and the cable force of the strut;Due to the construction error,the arch of the arch can be tilted.It is found that the inclination of the arch rib 5° will affect the internal force of the arch rib and the boom,but the impact is relatively small,and the contrast is inclined outward and does not roll.In both states,it is safer to lean inward.The influence of concrete super-party and less square on the cable force of the boom is most obvious;During operation,the rust and damage of the boom will affect the stress of the boom itself and also affect the force of other components of the bridge,thus affecting the safety of the bridge.It is found that the stiffness of the boom decreases with time.The influence of the ribs is not large,and the influence is relatively prominent in the arch,1/4,span,and3/4 position.The impact on the boom is obvious,especially the change of the side boom is the largest.Finally,I hope to provide some reference for the design and construction of this type of bridge.