| With the very rapid development of the society and economy,the construction of long-span bridges,especially long-span prestressed concrete continuous beam bridges increases brilliantly.There are different the construction methods for the PC continuous beam bridge.Among these methods,cantilever installation and cantilever casting have been used widely.This construction method results in the complex change of internal forces and displacements in the bridge.For ensuring the quality and the safety of the construction,the construction control is indispensable.On the other hand,creep is one of the material properties of concrete,by which constructions continue deforming over a long time under constant stresses or loads.If the load was maintained,the deformation would increase to several times of its elastic value.Creep brings not only additional deformation,but also redistribution of stresses and losses of prestress.The influence of creep on bridge structures is especially severe.The calculation of creep has become necessary in bridge design and construction.Besides,due to the poor thermal conductivity of concrete,the structure itself may be subjected to non-linear temperature gradient.The non-linear distributed temperature gradient will result in a considerable temperature deformation in the concrete bridge structure and cause thermal stress,large enough to make concrete structure crack.Temperature effects of the concrete structure has received more and more attention in engineering.Based on the Xinyongning Yong River Bridge with the span of(92m+168m+92m),the construction control,control error,concrete shrinkage and creep,and the temperature effects on the continuous beam bridge were studied in this thesis.The main contents are listed as follows:(1)Firstly,the development state of PC continuous beam bridges were reviewed,the research outline of the development state of construction control and the research of temperature effects were described briefly.(2)Secondly,purpose,control method and content,analytical method,effect factors,the error analysis and correction,finite element method of the construction control of the PC continuous beam bridge were summarized briefly.(3)Based on the actual project of the bridge,the finite element model of the cantilever construction process was established,and then,the deflection and the stress distribution state of the crictical sections under some key construction stages were analyzed,which included the largest cantilever construction state,closure construction of side spans,closure construction of mid span,second term dead load,shrinkage and creep of concrete and so on.(4)According to the project of the bridge.The deflection of cantilever end was calculated by using finite element method,the bridge alignment was obtained by setting corresponding points at the key section,and the stress of the control section at each construction stage was measured by using the pre-setting stress sensors.The results show that the bridge alignment and the test section stress from measuring and theoretically calculated values agree well,the internal forces and bridge alignment also meet the design requirements well.(5)The temperature effect of PC continuous beam bridge was analyzed by using the finite element method and using the different temperature gradient modes,taking from the specifications,the parameter identification method and field measurement.The results show that the exponential curve of temperature can be effectively used for the temperature gradient mode.And the parameters of the exponential curve can be obtained by using the parameter identification and field measurement.With the change of the parameter identification,the beam deflection and the key section stress change a little.(6)The patterns of temperature loads vary greatly because of the different temperature modes,so one needs use the measured data for considering the temperature effects when analyzing the structural internal force caused by the temperature. |
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