Research And Crack Angle Stress Analysis Reinforced Concrete Floor Slab

Presently, cast-in-place reinforced concrete floor slab (cast-in place slab for short following) has gradually replaced prefabricate slab because of its advantages like divided up easily, fitting for long span structure, good integrity and seismic performance. So the new slab has being the major format of roof. Meanwhile, crack problems come together. Along with the application of large-scale and new type structure system and the requirement for building function enhanced, crack problems in reinforced concrete structure become an issue needed to be dealt urgently. The plate angle cracks have been the common quality problems. Therefore, studying on the generating mechanism of this kind of crack, and discussing the regularities that influence on crack resistance are import to prevent this kind of crack.This thesis summarized researches status at home and abroad about reinforced concrete floor slab, and studied the factors of influencing crack expansion and cracking mechanism of floor slab by using theoretical analysis, simulated methods, references and practical engineering. The main contents are listed as follows:(1) Illustrating the mechanism and classification of concrete, and listing cast-in-place slab’s failure patterns, finally concluding that the oblique crack at corner of floor slab caused by temperature-shrinkage is the main form of the regular service phase and longitudinal crack paralleling with the side of the slab is the next.(2) Studying the factors that directly influence plate temperature shrinkage cracks according to the Study on temperature-shrinkage stress of concrete floor slab and simplify compute equations of temperature-shrinkage stress for cast-in-place reinforced concrete floor slab which is constrained at four corners.(3) Studying the single span slab that is constrained at corners by using the methods of numerical simulation, and analyzing the regularities of slab stress distribution impacted by these factors like temperature, openings on the floor, floor slab settlement, secondary beam septation and reinforcing bars.(4) Concluding the main reason for crack producing and the main factors impacting plate angle cracks, and putting forward some preventive treatments on shrinkage cracks in several ways of post-pouring belt’s setting, floor slab bars, same intensity replacement of steels, punched-floor slab, control measutes on side span oblique crack combined with practical project.