The Origin Of The Crack In The Cast-in-place Concrete Rib Shape Room And Against Crack Research

The crack of the cast-in-place rib shape room is the common quality question in the actual project.The existence of the question is difficult to achieve the inspection standard.It enormously affects reliability target of the construction product.Because of lacking the thorough theory cognition to the crack origin mechanism,the engineers and technicians widely pay attention to the question.The author has done the following research work in view of this topic.First,the author analysis initially the origin of the crack in the cast-in-place rib shape room.This may induce into following four kinds:(1) the vertical load causes crack;(2) the temperature stress causes crack;(3) the strong boundary constraint causes crack;(4) the stress concentration which forms in the hole position produces the crack;Second,the author using the theory of elasticity infers the control differential equation and calculates the stress of the rectangular thin steel plate under temperature load.It reveals the rule of the roof's stress distribution.Third,the author using the finite element method analysis the internal forces under temperature load and builds the roof's model in use of ANSYS software.It provides some valuable result for certain project.Fourth,the author proposes some measures against the roof's crack in order to prevent and reduce the crack's appearance.The author obtains some important achievement through the above research work.First,the convex-concave distortion of the roofing board is not by the temperature difference,but by the axis's average temperature.Second,the 70%of the roofing board's internal dehiscence force are caused by the temperature load,the 30%by the vertical load.The 80%of the roofing board's combined deflection are caused by the vertical load,the 20%by the temperature load.Third,the hole of the roofing board can cause the phenomenon of the stress concentration.