Research On The Time-varying Effects Of Long-span Concrete Cable-stayed Bridge In Service

Long-span concrete cable-stayed bridge, with its good performance of the structure andbeautiful landscape modeling are widely used in modern long-span bridge, but the concretecable-stayed bridge in service, of which the linear and the cable forces are more into thedesign of the state has undergone a large change. Based on the background of YueyangDongting Lake Bridge, the research on the large span concrete cable-stayed bridge isdeveloped in service during the time-varying effect.For the current shrinkage and creep prediction modes, the four groups (CEB-FIP90,ACI209(92), RILEM B3and GL2000) of shrinkage and creep prediction modes are choosento parameter analysis according to several important factors affecting the forecast of fourshrinkage and creep in the same conditionsThrough a series of shrinkage and creep test on experimental environment and naturalenvironment, the laws of C60high-strength concrete creep and shrinkage on experimentalenvironment and natural environment are identified, and some laws are analyzed by specimengroups of high-strength reinforcement concrete shrinkage and creep, and the ACI209(92)mode which do not consider the factor affecting the strength of concrete is modified, andtheoretical data are analyzed and compared with actual experimental data.The displacement transformation matrix of which each sub-units ultimately areassembled as combinations of pi-type element is derived, and the pi-type element isembedded in the ANSYS software to make use of UPFs platform to achieve a user-definedelement, and two examples show that computational analysis can obtain a better analyticalresults, and the user-defined element is more efficient resource. The creep and shrinkageeffects of Dongting Lake Bridge where the model is built by using the user-defined elementand beam188are analyzed in accordance with the ACI209(92)-X modified mode et al, andthe laws of internal forces and displacement on Dongting Lake Bridge are summarized underthe shrinkage and creep effects.In connection with temperature field of the concrete pi-section main beam, it showsthrough theoretical analysis that temperature field of the plates inside and outside surface is inthe time lag relationship, and the factors are researched on the main beam temperature field including the plate thickness, the thermal physical properties of the concrete as well as localnatural conditions by ANSYS and theoretical derivation, and the conclusion shows that thechange of the thickness of the roof and side ribs is limited to the temperature of the outersurface of the plate, and thermophysical properties of concrete is little effect on temperaturefield of the concrete beam, and the speed of wind has less impact on temperature field of theconcrete beam. According to temperature distribution of the Dongting Lake Bridge, ANSYSfinite element models are used as parametric analysis where the important parameters affectthe temperature field of the Dongting Lake Bridge.According to the phenomenon where steel cables are susceptible to damage and tend tostress relaxation in service, it is essential to take damage characteristics into account instructural analysis. By introducing equivalent-strain principle and geometrial damage theory,the corrsion mechanism of cable is described and a formulation solving the boundry problemwith the governing differenial equation of the service cable is formulated. With the proposedmethod, cable damage as well as stress relaxion has been taken into consideration, whichprovides a reliable technique with analyzing the geometric nonlinerity of cables of existinglong-span cable-stayed bridges.