The Research On Closure Related Problems Of High-pier And Large-span Curved Continuous Rigid Frame Bridges

Continuous rigid frame bridge has been widely used in bridge construction in China because of its advantages of simple construction technology,good seismic performance,stable and comfortable operation.However,curved continuous rigid frame bridges are more flexible to adapt to the terrain than linear ones.Due to less construction site constraints,viaducts and overpasses in on-ramp cities as well as mountains and hills can be seen everywhere in China.Closure sequence and closure segment construction order to determine the quality of curve rigid frame bridge design and construction,it has a great influence on the internal forces of the dead load of main girder bridge.Because the stress of curved bridges is more complex and there are many influencing factors,the existing researches mainly focus on the problems related to the closure sequence of linear bridges and the construction of the closure section,while the researches on the long-span curved continuous rigid frame bridges with higher piers are less.In this paper,the main bridge of Wugong bridge with high-pier and long-span curve continuous rigid frame bridge is taken as the engineering background,analyzed several key problems of bridge closure,the main work completed and the results are:(1)This paper summarizes the development process of curved rigid frame bridges by referring to relevant data,studies the closure sequence of rigid frame Bridges and the key problems in the construction of the closure section,and briefly expounds its structural characteristics and common theoretical analysis methods.(2)Finite element analysis software Midas/Civil is used to establish the structural finite element models of successive closing orders of the first side-span closure followed by the middle span closure,and the simultaneous closing orders of the middle span closure to study the influence of the closing order on the main bridge of Wugong bridge;At the same time,in order to discuss the influence law of curvature radius on the stress and deformation of rigid frame Bridges with different closure sequence curves,the curvature radius of 1000m and 500m is modeled and studied without changing other parameters.(3)After changing the sequence of closing for multiple spans in the original design,the closing thrust in the original design should be adjusted accordingly.Based on the principle of influence matrix method and least square method,using Midas/Civil to establish jacking force model,the optimal jacking force was calculated with MATLAB program by taking the vertical unbiased position of the pier after ten years of shrinkage and creep as the objective function,it is found that the main pier is in a favorable state of axial compression after ten years of bridge formation under the optimized jacking force.(4)Using large-scale finite element analysis software ANSYS,through the way of combination beam unit and entity unit model of main structure modeling analysis,studied the four closures segments of pouring concrete at the same time in the process of condensation sclerosis caused by the change of environmental temperature on the mechanical effect,the study found that the stress of the side span closure segments concrete is greater than the midspan,and the maximum stress was on the side span closure segments at the bottom of the box girder of the roof of the central and flange plate end position,finally aiming at the problem of the temperature change of puts forward the countermeasures to solve these problems.