Analysis Of Shrinkage And Creep Effect Of Long-span Prestressed Concrete Continuous Rigid Frame Bridge

In recent years,with the vigorous development of China's transportation industry,long-span prestressed concrete continuous rigid frame bridges have been widely used in southwest China due to the uneven terrain adaptation,strong spanning capacity,simple and convenient construction,etc.A large number of high pier and long-span prestressed concrete continuous rigid frame bridges have been built in China,especially in western mountainous areas.However,in the construction process of long-span prestressed concrete continuous rigid frame bridge,there are also a series of technical problems,which will seriously affect the construction quality of the bridge if they can not be well solved.The effect of concrete shrinkage and creep on structural deformation and stress is always one of the difficult technical problems in the construction of prestressed concrete continuous rigid frame bridges.Because of many factors,the shrinkage and creep effect of concrete is very complex,and in many cases it often shows serious randomness,so it is difficult to accurately grasp the influence of shrinkage and creep effect on structure in practical engineering.Because of the complexity of the construction site stress measured at the site is often not so accurate.How to accurately predict and solve the effect of shrinkage and creep on structure in practical projects is of great value to guide the construction of practical projects.Based on the existing research results and taking the Bridge in Yunnan Province as the engineering background,the finite element model for bridge construction control calculation is establishes by using Midas Civil finite element software.Through calculation and analysis,the shrinkage and creep effects of the pre-stressed concrete continuous rigid frame bridge in the whole construction process and in the completed state are mainly studied.Specifically,the research contents of this thesis are as follows:(1)The research status of concrete shrinkage and creep is extensively investigated,and the mechanism of concrete shrinkage and creep and the main factors affecting concrete shrinkage and creep are summarized.(2)The similarities and differences of concrete shrinkage and creep prediction models at home and abroad are compared and analyzed,and the main factors affecting the prediction models and the application scope of each prediction model are analyzed.It provides a basis for choosing appropriate prediction models when studying concrete shrinkage and creep effects in practical projects.(3)Taking the Bridge as the engineering background,the whole bridge calculation model is established by using the finite element analysis software Midas Civil.Four different norms of shrinkage and creep prediction models are selected to compare and analyze the influence of the main parameters of the bridge in the construction stage,such as stress,internal force,pre-arch,loss of pre-stress and deflection.The calculation results of different norms are summarized and summarized.The reasons for these differences are preliminarily analyzed.(4)Taking the Bridge as the test object,a "continuous"-stress testing method by using wireless tranfer of test data is proposed,which effectively reduces the influence of surrounding environmental factors on the test results.(5)By comparing and analyzing the calculated theoretical values with the measured values,considering the influence of shrinkage and creep on the stress and deflection in the construction stage and the completion stage,the application scope and advantages and disadvantages of each prediction model are summarized.