Stochastic Analysis And Reliability Analysis Of Shrinkage And Creep Effects For Long-span Prestressed Concrete Cable-stayed Bridge

Shrinkage and creep are the inherent characteristics of concrete material with numerous influence factors such as time variation and uncertainty. Long-span PC cable-stayed bridge is a kind of structure which affected sensitively by the concrete shrinkage and creep, hence it has great practical significance to study the shrinkage and creep effects of long-span prestressed concrete cable-stayed bridge in the probability level, reflecting the uncertainty of the concrete shrinkage and creep effects objectively.The whole work of this dissertation consists of four parts. The first part introduces the concept of the concrete shrinkage and creep is introduced and the mechanism and influencing factors of the concrete shrinkage and creep are summarized in the first part, the calculation theory of concrete shrinkage and creep is inductived in this part as well. Two kinds of common methods for analyzing static stochastic structures which consists of perturbation stochastic finite element method and monte-carlo stochastic finite method are expressed and proposed a kind of new approach named response surface -monte carlo method is proposed in the second part. The simulation analysis of the construction process for Ganzhuxi Bridge of orbital highway in Guangzhou is carried out using orderly-erecting analysis method in the third part. Finally the stochastic analysis and reliability analysis for Ganzhuxi Bridge of orbital highway in Guangzhou which considering the concrete shrinkage and creep effects using response Surface-Monte Carlo method is performed.The conclusions of stochastic analysis and reliability analysis for Ganzhuxi Bridge of orbital highway in Guangzhou with the concrete shrinkage and creep effects considered are as follows:(1) Smaller variability of the structural stress and cable-stayed cable force is observed due to the randomness of calculation parameters of the concrete shrinkage and creep causes, On the contrary, comparatively large variability of the deformation of the main girder and main tower is observed.(2) The randomness of ambient relative humidity has the most important influence on the variability of the concrete shrinkage and creep effects (stress, deformation, cable force) and the randomness of compressive strength of concrete and loading age has relative weaker influence. However, the randomness of theoretical thickness of the component and age starts to contract has the weakest influence on the variability of the concrete shrinkage and creep effects.(3) When the value of the corresponding deviations allows the smaller value, effect of concrete shrinkage and creep control objectives can not be intended probability (failure probability) greater. Allowable values for the same deviations, concrete construction completed earlier due to contraction of the longer shrinkage and creep, therefore, the greater the corresponding failure probability, the smaller the failure probability and vice versa. On the other hand, the intended goal of structural response control 90% of reliability that is acceptable for the large-span prestressed concrete Cable-stayed structure, at this point the value of the deviation is considerable. Therefore, it is quite necessary to perfom reliability analysis of shrinkage and creep effects for the long-span PC cable-stayed bridge.