Concrete Creep Analysis Of High-rise Building In Construction Process

Currently, most researches about high-rise building structures focus on structural analysis and design. The influence of construction process on structural internal force and deformation is relatively less studied. Usually, the analysis of structure is based on the whole model which has already been built, and then applying the load on structure analyzes the load condition. However, the high-rise building structure is built step by step in construction, and the structure of the stiffness and vertical load also changes with the construction. Due to the creep characteristic of concrete material, concrete column and core tube composed of shear wall will emerge large vertical deformation in the whole construction process. Whereas construction sequence and the leading number of layers of concrete core-tube and the influence of internal force and deformation of structural members caused by concrete creep are often ignored, thus the vertical deformation and internal force of structural members do not match with the actual situation. Meanwhile, the properties of concrete creep and shrinkage of each part of structure are different as well as loading time, and the problem of creep and shrinkage of high-rise building structure will become very complicated, so it is very necessary to carry out the analysis considering construction process and concrete creep and shrinkage for a high-rise building structure.When engineers calculate the stress of construction stage of high-rise building structure, the influence of creep effect and the age of concrete must be considered. In this thesis, the user subroutine of concrete creep is coded with FORTRAN programming language based on the concrete creep theory of Zhu Bofang’s calculation formula. Then the user subroutine of concrete creep is applied to ABAQUS software. The correctness of subroutine is verified by comparing with the experiment results. And the influences of reinforcement ratio, axil compression ratio and concrete strength grade on the vertical creep deformation of concrete column and shear wall are analyzed.In this thesis, a high-rise building structure is established in ABAQUS software. Firstly, the analysis of the whole loading method and the precise construction simulation method is respectively carried out. The results show that the traditional whole loading method cannot accurately reflect the stress condition of structure and do not match with the actual situation. Secondly, calling the user subroutine of concrete creep in ABAQUS software analyzes the high-rise building structure on the basic of the precise construction simulation method. The analysis result indicates that engineers should pay attention to the construction process and concrete creep and shrinkage’s influence on the deformation of vertical component of high-rise building structure.