Research On Construction Methods Of Cast-in-place Box Arched Bridge's Sub-layer

Long-span arch bridges are emerging in rescent years, casting for the long-span arch bridge's box-section arch ring, especially for the indeterminate structure of the non-hinged arch, choose a reasonable construction method not only can save substantial costs,but can guarantee the stability of the bridge and to improve construction safety. For the different of the construction layer and segment ratio and order differently, construction stages of internal force calculation and the arch of the force is also very different. But how to sub-layer, segment identify, the main factors are structure of the internal force should be reasonable,the construction organizations,the arrangements,the use of equipment and construction technology, all of this should be comprehensive consideration. How to sub-effective control for long span arch ring of the box section sub-layer in the construction stages, to ensure the safety of the arch bridge alignment and internal forces to meet the design requirements, how to reduce arch size while not changing the design of the case, keeping arch changing conditions in small deflection smoothly together and to eliminate sub-loop tensile stress caused by improper, is the purpose of this study.Based on the large amount of data access and collection of technical points on the arch layer, segment and method of the placing order, combined with the actual construction,Anasy by a variety of software get a more suitable construction method for such a kind of bridges. Also by comparing the error occurred for the monitor data and theoretical data in the construction processing, get a better ways for such bridges. Through analysis we can get the following conclusions:(1) Concreting layer by layer and segment by segment should be combined use in long-span arch bridge box section construction. The way more conducive to project force structure, and can be low cost, in a similar span bridge, the first segment use 2.5m more better.(2) The proportion of sub-paragraph layer by layer and segment by segment shall be based on the actual situation, considering the time, cost, security, the overall arrangement for construction and other factors combine to the calculation model.(3) During the process of pouring concrete in the arch ring,should take some measures to keep uniform of concrete mass, so does the arch force, and to control the shrinkage stress., if necessary take increase the template, adjust the concrete mix and other measures.(4) During the control of the installation of arch and the falsework should consider the non-elastic deformation and the elastic deformation, combined with permanent loads, temperature changes, shrinkage and creep of concrete under the action of displacement values in analysis.(5)The concrete creep effects between rings can be contrled by reducing construction time andincrease the stirrups(6)The arch system s foot negative moment should be eliminated through consolidation or other effective means. This study use SAP2000, Midas, Abaqus to build the model based on the data obtained during construction of the key processes to guide the construction, At the same time,use the practically measured data to ensure the result of the finite element method.Based on the analysis above,obtain the, inner-force, deformation, stability of the bridge. Then, a number of optimization scheme by means of pouring arch was mentioned, so as to obtain the optimized sub-box section arch ring-ring casting ratio, sub-placement order and to benefit the design and construction.