Experimental Study On The Effect Of Complex Internal Constraints On Early Shrinkage Of High Strength Concrete

At present,with the continuous improvement of my country’s economic level,the number of super high-rise buildings is also increasing.The steel plate-concrete composite shear wall hybrid structure has become more widely used in super high-rise buildings,mainly because of its high bearing capacity and at the same time it can effectively use the building area.Compared with the general reinforced concrete shear wall,The steel plate-concrete composite shear wall has many advantages,including seismic resistance,good displacement ductility,and high rigidity.However,due to the use of high-strength concrete,the general strength is C60 and above,and its water-cement ratio is lower.The complex constrained environment with steel bars,steel plates and pegs leads to a greater risk of cracking in the early days of steel plate-concrete composite shear walls.The cracking of concrete is easy to make the interior affected by the external environment,such as corrosion of steel bars,harmful media will enter the interior,which will greatly reduce the durability and integrity of the concrete structure.In view of the insufficient research on the shrinkage performance of concrete under internal constraint at home and abroad,and the common cracking phenomenon in the early stage of steel-concrete composite shear wall,this paper analyzes the early shrinkage deformation law of concrete through the experimental study of internal confined concrete,evaluates the early cracking risk of high strength concrete,and reduces the early cracking phenomenon of steel-concrete composite shear wall in the current super high-rise building.The main research contents and conclusions are as follows:(1)Experimental research was conducted on the shrinkage deformation of concrete and the basic mechanical properties of concrete under the constraints of steel bar,steel plate and stud.The main variables considered in the experiment are steel plate thickness,steel bar diameter,peg diameter,peg length,peg spacing and maintenance conditions.The main conclusions obtained through analysis of test data and phenomena are: the shrinkage deformation of high-strength concrete under the constraints of steel plates,steel bars and studs,with the thickness of the steel plate,the number of studs,the diameter of the studs,the length of the studs and the diameter of the reinforcement Increase,the shrinkage deformation of concrete decreases.(2)The internal cracking stress is used to analyze the early cracking risk of constrained concrete.The analysis shows that: as the thickness of the steel plate increases,the early cracking risk of concrete increases;as the number of bolts,bolt diameter and bolt length increase,the concrete cracks The risk increases;as the diameter of the steel bar increases,the risk of early cracking of the concrete increases.