A Large Reinforced Concrete Slab Crack Control And Research

With the development of large scale structure,super large reinforced concrete structures have been used more and more widely.For the super large reinforced concrete slab, the shrinkage and temperature deformation of concrete during the stage of construction are the main reasons to the occurring of cracks, so the research and analysis on the crack control of concrete shrinkage and deformation on large scale concrete has great significance.At present the common measure of engineering to the crack control is to set post-poured belt or adopt prestressed concrete to control the cracks. And the practical engineering of this paper is to adopt the seamless design and construction method of setting expansion reinforcing belt to replace the post-poured belt,which has no domestic related standardization and improving design methods, so there are a series of problems need to be solved such as the selection of expansive agent,the determination on the width of expansion reinforcing belt, its location and amount,and the determination on the restricted expansion rate and so on. This paper based on background above, the research of the paper mainly includes the following:(1) Introduce the research progress of concrete shrinkage, concrete creep, and temperature stress get the calculation method of the temperature stress,shrinkage deformation and creep of concrete structure through the theoretical analysis on the super large reinforced concrete structure under the effect of temperature, shrinkage, and creep.(2)The paper used the ANSYS finite element software to make respective analysis and comparison on the super large reinforced concrete slabs without any anti-crack measures and with the expansion reinforcing belt;firstly, use ANSYS to establish the finite element model of super large reinforced concrete slabs without any anti-crack measures, get the related structural stress and deformation regular pattern through imposing the most adverse temperature to the structure,which refers to that the maximum stress value appeared on the center of slab and present the stress concentration region with two oval overlayingdistribution,four corners of slabs also have stress concentrating phenomenon but the area is small. The maximum structural deformation appeared at the top of the structure,with the reduction of the distance to the axis,the deformational also gradually decreased. Secondly,use ANSYS to establish finite element model of super large concrete reinforced slabs with expansion reinforcing belt,analyze the stress and deformation regular pattern of the structure at different parameters of belt width,location,and quantity and compare the results with the slabs without any anti-crack measures,the results showed that:The stress and deformation of the structure decreased after setting expansion reinforcing belt, and the stress reduced32.8%,which could reflect that the expansion reinforcing belt has compensation contraction capacity,and can prevent the early crack of super large reinforced concrete.(3) Based on the results of finite element analysis on the practical engineering,combining with the crack control principles of “prevention”,“resist” and “set” and existing crack control measures,the paper proposed the crack control measures for the project from design, construction and materials and other aspects.