Study On Creep Effect Of High-rise Reinforced Concrete Structures Under Long-term Load

In recent years, high-rise buildings are increasingly adopted along with the rapid population growth and the rapidly-developed economy. Due to high building structures generally have characteristics of large dead weight and long construction period. Compared with the general structure, the effect of creep in tall buildings are more apparent, so it is very necessary to carry out the analysis considering construction and concrete creep for a high-rise building structure.This paper mainly discusses the analysis method of concrete structure under long-term vertical loads and has carried out the following work:Firstly, this paper discussed the mechanism of concrete creep and analyzed four kinds of prediction models of concrete creep by compared the number of parameters; the applicable conditions and creep value under a specific condition.Secondly, paper obtained a conclusion that the Construction stage simulation should be adopt when we calculate the vertical load effect of high-rise building.Then based on the construction stage simulation, this paper calculated the concrete creep effect, and derived a Creep prediction model to estimate the creep effect of the reinforced concrete structures, according to the equation of equilibrium and Strain compatibility equation in a cross-section. On the basis of CEB-FIP(MC1990) prediction model using Matlab program to fit the equivalent elastic modulus, the equivalent relative humidity of the ambient environment and the equivalent notational size of member, So SAP2000, a finite element analysis software, can make good use of this model to analyze the creep of RC structure.Finally, the paper discussed the calculation of internal forces and deformation of concrete structures under a long-term vertical load.by establishing classical Frame-Tube structure 3D model, some conclusions which have been discussed above have been checked in this paper, and by comparing the impact of vertical deformation in different construction speeds, curing time, relative humidity of the ambient environment and reinforcement ratio to put forward reasonable proposals for controlling structural vertical deformation in design and construction process.