| Arch bridge, as one of the oldest bridge types, has a history of more than threethousand years. Reinforced concrete box arch bridge, as its grand appearance,cost-efficiency, has been widely used in bridge engineering. Non-bracket cable-hoistingconstruction method is the one of the most widely used one for the construction of thisbridge type. As in each construction stages of the construction, the bridge structurechanges, which makes the internal force and displacement of the bridge structure morecomplex during in the construction process. In order to ensure that the internal force andlinearity of the bridge meet the design requirements, it is necessary to carry on aconstruction monitoring.The paper introduces the development of domestic and abroad long-spanreinforced concrete arch bridges as well as their present situation, then summarizes theexisting methods for the construction of long-span reinforced concrete arch bridges andelaborates the characteristics of non-bracket cable-hoisting construction method and thecomposition of the hoisting system. Based on the above points, the paper furtherexpounds the content of construction control and its necessity in the hoisting process ofthe bridge. Then the main aspects and contents of construction control during theprocess of non-bracket cable-hoisting construction method cables are introduced. Thecable forces and its linear calculation methods are summarized, and the linearadjustment method in the process of cable hoisting arch bridge construction areintroduced.The paper, taking Longmen Bridge constructed by non-bracket cable-hoistingmethod in Liangjiang New Area, Chongqing, introduces the background and generalsituation of the project According to its construction process, the monitoring key pointsin the construction monitoring of the bridge are demonstrated. In this paper, through theestablishment of finite element calculation model of the Longmen Bridge, the followingwork has been conducted for the linearity control and monitoring in the constructionprocess of the bridge:①Through comprehensive consideration of various influencing factors after theconstruction of the arch ring on the setting of the arch ring’s pre-camber, the paper givesout the calculation method of pre-camber of concrete arch bridge constructed bynon-bracket cable-hoisting method. Combined with the construction of LongmenBridge, the paper quantitatively calculates the influence of such influencing factors asthe static constant load, live load, temperature drop, creep and shrinkage on the linearityof arch ring through establishing finite element models of the bridge. And reasonablepre-camber of the arch ring is calculated according to the calculation method mentionedabove. Based on the calculated value of pre-camber, the control and monitoring of theprefabricated linearity of the arch ribs are carried out by construction lofting.②Through comprehensive consideration of various influencing factors during theconstruction of the arch ring on the setting of the arch ring’s pre-camber, combined withthe construction of Longmen Bridge, the paper quantitatively calculates the influence of various influencing factors on the linearity of arch ring, for example, the setting of thewind cable, the displacement of the cable tower, the pre-camber of the arch ribs duringhoisting and the removal sequence of the cables. By calculating the reverse value of allthe influencing factors considered, the pre-camber value of the arch ribs during hoistingconstruction is set.③The paper also transversally investigates the influence of thewind cable and the removal sequence of the cables on the linearity of the arch ring byvarying the initial tensile force of the wind cables and the removal sequence of thecables, which can be of guidance to the construction of similar bridges.④Throughcomprehensive consideration of above said factors, the control basis for the linearitycontrol and monitoring of Longmen is obtained in this paper, so as to guide and monitorthe actual construction process of the bridge. |
