Design Method And Engineering Application Of Super-Long Cast-in-Site Reinforced Concrete Hollow Floor

Super-long cast-in-site reinforced concrete hollow floors have the characteristics of super-long cast-in-site reinforced concrete structures and hollow floors. Therefore, the both technical characteristics should be taken into account during structural design and engineering application.The non-load crack is the key problem of super-long cast-in-site reinforced concrete structures. Through the various non-load deformations of concrete floor and the corresponding stresses fully be studied, the main factors that induce to crack are as follows: the cracking stress mainly induced by the change of temperature, the shrinkage of concrete and the residual stress caused by hydrate temperature.Reinforcing concrete wall, grooving a stress-release slot in super-long cast-in-site reinforced concrete floor and adopting tiny expansive concrete are good measures to control the cracking. Analyzing the beam-column constraint coefficient along the length shows that the efficient of reinforcement can be discussed by analyzing the fully constrained reinforced members. So based on this conclusion, the relationship of concrete strain and stress to the steel ratio, the relationship of crack width to steel ratio, quantitative relationship of crack width to crack number and the rational steel ratio are discussed in this paper. Furthermore, the results prove that setting stress-release slot is an effective measure if the length of reinforcement concrete basement slab-wall is limited in reason. Finally, how to control cracking by controlling the temperature of tiny extended concrete is discussed.Case-in-site reinforced concrete hollow floor is a new type floor, which is widely used in practice in recent years. High strength thin-wall hollow were placed in the floor by a certain rule, which could get lower deadweight and higher carrying capacity at the same time and enable the floor span more space. The flexural function is selected, which consists of the trigonometric series and polynomial expression. The flexural function satisfies the governing differentiable equation of orthotropic plate and boundary conditions. Therefore the general solution of orthotropic rectangular plate is obtained. Through elastic theory, a calculation model is made to analyze mechanic behavior and the distribution of inner moment of the cast-in-site reinforced concrete hollow floor.The methods of super-long cast-in-site reinforced concrete hollow floors are applied to practical engineering such as Changsha Tongcheng Commercial Plaza. Temperature stresses are analyzed by universal finite element program of ANSYS. The reasonable structural model and disposal and other various availability measures are be taken into account during the structural design, therefore, large social and economic values are obtained. Some reasonable advices about the design method and construction rules about the case-in-site reinforced concrete hollow floor have been put forward .