Research On Prestress Loss Of Containment Structure Considering Concrete Creep

With the increasing demand for energy,clean energy led by nuclear energy has been paid more and more attention.In this trend,China's nuclear power has developed steadily,and nuclear power occupies a place in China's energy territory.As a barrier to ensure the safe operation of nuclear power plant,the importance of containment is beyond doubt.However,at present,the research on concrete creep and prestress loss of containment structure is less and insufficient,and the research method is not comprehensive enough.Based on three concrete creep models,this paper considers the influence of concrete creep on the mechanical properties of prestressed containment including the prestressed reinforcement system with complex spatial line shape in the whole process of pouring,tensioning and service,and the mechanical properties of containment structure considering prestress loss under internal pressure are studied.The main contents are as follows:1.Based on the three commonly used international concrete cre ep calculation models,the CEB-FIP model code 90,the FIB Model Code 2010,and the gl2000 model proposed by professors Gardner and Lockman of ACI,the creep calculation model of variable stress concrete is derived.By using ABAQUS finite element analysis software,the time-varying mechanical properties of the containment structure in the process of concrete pouring are analyzed.2.In this paper,the time-varying mechanical properties of the containment structure considering the influence of creep in the process of prestressed reinforcement tensioning are systematically analyzed,and the weak parts of the containment structure in the stage of tensioning are obtained.Compared with the situation without considering creep,the influence of creep on the mechani cal properties of the structure in the process of prestressed reinforcement tensioning is revealed.The effectiveness of the simulation method is verified by comparing the simulation results with the measured results.3.The mechanical property analysis of the containment structure considering the creep effect under different service life is carried out,and the change rule of the mechanical property of the containment structure is obtained.The stress loss prediction analysis of the prestressed reinforcement caused by the concrete creep with the design life of 60 years is carried out,and the influence of different creep models on the analysis result of the prestress loss is compared.On this basis,the prestress loss caused by various factors is considered,and the prestress loss of containment structure under the whole life cycle is predicted and analyzed.4.Based on the prediction results of total prestress loss,the whole process mechanical performance analysis of containment structure considering prest ress loss under internal pressure is systematically carried out from functional failure to structural failure.The failure mode,cracking internal pressure and ultimate internal pressure of the structure under different service life are obtained,and clarified the influence of time-varying prestress loss on the mechanical properties of containment structures.