Three Dimensional Nonlinear Simulation Analysis Of Temperature Shrinkage Effect Of Super Long RC Frame Structure Considering Construction Process

In recent years,with the rapid development of engineering construction and economy,over-long RC frame structure is increasingly widely used in public buildings and high-rise buildings.Because people’s requirements for building beauty and integrity are also improved,designers often don’t set or cancel expansion joints in buildings,and solve the problem of temperature shrinkage cracks by setting post pouring.However,at present,the engineering practice of over-long RC frame structure with post cast strip leads the design theory,and the three-dimensional simulation research on the influence of construction process on the structure temperature shrinkage effect is rarely involved.In this paper,considering the construction process,three-dimensional nonlinear simulation analysis on temperature shrinkage effect of over-long RC frame structure with post cast strip main research contents is as follows:(1)The research on temperature shrinkage effect of over-long RC frame structure in our country and abroad is reviewed.The method to determine the calculated temperature difference in the nonlinear analysis of temperature shrinkage effect of over-long RC frame structure considering the construction process is put forward,and the nonlinear analysis of temperature shrinkage effect should be carried out according to the combination of temperature action,dead load,live load,etc.(2)Based on the theory of three-dimensional solid degradation virtual laminated element,a dual nonlinear(geometric and material nonlinear)finite element analysis method is developed,which can consider the temperature shrinkage effect in the construction process.The method can consider the construction process by stages of the structure,realize the three-dimensional collaborative simulation of beam slab column space,and divide the solid element into blocks(concrete and steel)in the model In order to set different material temperature or linear temperature gradient field,and consider the difference of linear expansion coefficient between reinforcement and concrete.The necessity of calculating the temperature shrinkage effect of a space single-layer frame structure considering the construction state and not considering the construction state is verified by calculation and analysis.(3)Using the nonlinear finite element analysis program of the three-dimensional entity degradation virtual laminated element,the influence of different post cast strip spacing and retention time on the temperature shrinkage stress of each span of single-layer over-long reinforced concrete frame structure is analyzed,and then the effective effect of floor reinforcement ratio,floor thickness and concrete strength on the post cast strip spacing is analyzed within the common post cast strip spacing range It provides a reference for the retention time and spacing of post cast strip in the construction process.(4)Taking a two-story over-long RC frame structure factory in southern China as the research object,considering four different construction processes,the three-dimensional nonlinear simulation analysis of the temperature shrinkage effect of the structure under the combination of overall temperature difference and vertical load(dead and live load,etc.)is carried out.In the analysis,the seasonal temperature difference of different construction progress,the setting and closure of post cast strip are considered.Through the calculation results of the overall deformation of the structure and the stress,deformation and cracks of the beam,plate and column components,this paper discusses the influence of different construction processes(no post pouring belt and different post pouring belt setting methods)on the temperature shrinkage effect of the structure.According to the results of calculation and analysis,the reduction factor β of construction measures(setting post cast strip)in the simplified analysis method of temperature shrinkage effect of over-long RC frame structure considering different construction process is calculated.(5)Based on the above research,the finite element analysis program of 3D solid degradation virtual laminated degradation element is used to analyze and study the effective control effect of different temperature reinforcement configurations of overlong RC frame structure considering the temperature shrinkage stress in the construction process..Through the above research,the conclusions of this paper can provide reference for improving the theoretical research of temperature shrinkage effect and crack control of over-long RC frame structure.