Studies On Mechanical Properties Of Several Critical Processes In Closure Segments Of High-pier And Large-span Of Rigid Frame Bridge

The construction of the closure segments of the long-span bridge is one of the most key working procedure, and for continuous rigid frame which is multiple indetermination system,it is difficult to adjust its linear and internal force once they were closed, so closure segments construction should be controlled strictly,its quality has direct effects on the bridge.This paper focus on the key problem of closure segments construction of long-span continuous rigid frame bridge,which is based on Guizhou Yuqing to Meitan secondary highway rebuilding project called Da wujiang grand bridge , using large finite element software for analysis, researches and discusses the key problems of the different temperature effect on the internal force,horizontal pre-exerting problems of closure section,the influence of merchant steel skeleton reinforced welding etc, introduces the continuous rigid frame construction monitoring technology. This paper mainly does the following aspects of work:(1)summarizes the features and trend of development in modern times of the continuous rigid frame bridge .(2)In view of the problems of pier deviation and internal force of the piers' top becomes obviously bigger in the later period of operation in bridges , we can carry out pre-exerting method before the closure of the middle-span, using force method to simplify the theoretical calculation model of continuous rigid frame Bridges, and theoretical deduces the relationship between pre-exerting pressure and pier deviation. In order to simplify the above computing of relationship, using least-square method to fitting variable stiffness integral in theoretical model into cubic polynomial curve, this fitting curve method has high computing accuracy. Jacking force of pre-exerting reasonably can effectively control the bridge pier deviation and optimize internal force of the structural.(3)Compared the connection mode of the common skeleton of continuous rigid-framed, and calculated the minimum cross-sectional area of locking skeleton reinforced in a closure segment in theory,analysed the stress variation of the concrete of closure segments before and after skeleton reinforced applied for loads, and demonstrated the conclusion that the skeleton reinforced could partially replace the concrete of closure segments to bear loads and prevent concrete from crack.( 4 ) According examples, at present the principal problem of continuous rigid-framed closure is the temperature influence,and analyse that temperature directly affect bridge internal forces and the quality of final bridge from the normative. Taking wujiang large bridge as an example, fitted the temperature gradient curve, and computed the variation of stress and displacement in closure section under the action of temperature gradient .Result shows that, when the larger the temperature gradient is, the larger the temperature stress produced inside the structure is.