| With the implementation of the strategy of " building China into a transportation powerhouse ",the construction of infrastructure in the western mountainous areas is constantly stretching.Meanwhile,how to cross the mountain valleys has become a regular problem we have to face.Concrete-filled steel tube arch bridge plays a considerable role in the construction of western traffic network for its superior mechanical performance and exquisite appearance.At present,the vast majority of concrete-filled steel tube arch bridges in China are constructed by cantilever assembly method.In spite of the in-depth research on the control of segment-shaped arch ring construction process that a majority of scholars have carried out,the discussion on the influence of segment-segment splicing error and the correction method is still lagging.Herein,in terms of the stress-free state method,the control points in the process of segmental forming of arch ring are analyzed,the causes as well as the influence rules of splicing errors are delineated.Furthermore,the adjustment and optimization methods of arch ring considering splicing errors are established.The main work and conclusions of this thesis are as follows:(1)Based on the principle of stress-free state method,the control points of concrete filled steel tube arch bridge in segmental forming process are analyzed,including arch foot installation state,segmental splicing relationship and stress-free closing form.In the process of construction,the relationship between the three elements can be restored without stress to achieve high quality arch formation.The influence of arch foot Angle error and closing length error on arch alignment is analyzed.Although cable force does not participate in the ultimate force of arch bridge,it is the key to realize stress-free arch formation of arch ring.(2)The source and transfer law of splicing errors are analyzed,and the influence law of splicing errors on the segmenting forming process and arch state of concretefilled steel tube arch bridge is revealed.The conclusions are as follows: for process cable force which is under the same initial error,the closer the splicing error is to the arch foot,the greater the influence on process cable force is.The cable adjacent to the splicing error is most affected.For the arch state,the closer the splicing error is to the arch foot,the farther the stress state deviation is after the arch is formed.The closer the position generated by the splicing error is to the mid-span,the greater the absolute value of the alignment deviation after arching.The two error forms of upward deflection and downward deflection have the same effect law on the arching process and state.When the splicing error increases,the errors of cable force,stress and arch formation basically increase year on year.The total deviation caused by the coupling of multiple splicing errors is equal to the linear superposition when a single error occurs.(3)An arch ring optimization method considering splicing errors is established.In terms of non-stress parameter adjustment,the control ideas and methods of splicing errors in practical construction are analyzed.Additionally,the feasibility of the control methods is identified.The matrix relationship between the control mode and the arch line is established,and the optimization method as well as the flow of the complete splicing error are proposed.(4)Combined with the practical bridge,the feasibility and effect of the optimization method are identified.The results show that: for different positions and diverse forms of splicing errors,the proposed method can play a good correction effect,and realize the optimization of arch alignment and stress state.For excessive splicing errors,sacrificing part of arch ring stress can further reduce the peak value of linear errors.The precision,thickness of gasket and whether the stitching error can be recognized in time will affect the final optimization effect. |
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