Research On Key Technology Of Intermittent Construction Of Upper Super Long Concrete Structure

At present,the superstructure of various large buildings is usually a long-span super-long concrete structure.How to ensure that the superstructure will not crack due to temperature and contraction deformation during construction and service is the key point for structural design and construction.In this paper,based on various influencing factors that may occur to super-long concrete structures during the construction and service process,and combined with practical engineering cases and field tests,have a large number of engineering statistics,experimental studies and theoretical analysis of concrete shrinkage stress and intermittent construction organization.The main research contents include:(1)Inductively collate the relevant theories and norms of temperature and shrinkage deformation of concrete structures,and the reason of crack on the super-long concrete structure was analysed,and combining the statistical method of intermittent application situation,all kinds of temperature differences effect on the upper of super-long concrete structure may face were put forward,based on the constraint mechanism of super-long concrete frame structure,the intermittent time and block length are studied.(2)Based on field trials and extensive engineering statistics construction data,and according to the characteristics of its upper super-long concrete structure contraction,the shrinkage process is divided into three stages,the effect of temperature difference value basis and calculation method of the upper frame beam slab were analyzed by stages,which provides the academic basis for the further study of the upper intermittent time of super-long concrete structure.(3)The calculation theory of temperature stress of the frame structure of wang tiemeng and the finite element analysis were combined,and the shrinkage stress of the super-long concrete frame structure is calculated and analyzed,by which,the intermittent effect value of different interval time and block length were obtained,which provides theoretical basis for the key technology of intermittent construction.(4)based on the measured statistics of the beam and slab in a engineering case,the variation rule of the restrained strain of the super-long concrete frame structure was studied and analyzed,and the influence coefficient of the prestress on reducing the contraction stress of the structure was obtained through theoretical calculation and comparative analysis of the test results.(5)Through a comprehensive analysis of a large number of engineering construction data and theoretical calculations,determine reasonable construction organization arrangements,intermittent time and length of block casting and other additional measures to ensure the safety of the upper super-long concrete structure during construction and use,and prevent the structure cracks due to the shrinkage stress exceeding its tensile strength.The results of this paper propose a feasible calculation method of block length,interval time and maximum shrinkage stress of the structure,which can provide effective technical guidance for how to reduce the shrinkage stress during the construction of the upper super-long concrete structure,it provides a theoretical basis for the key technology of intermittent supercritical concrete structure construction,and has an important guiding role for intermittent construction.