Study On Calculation Models Of Cracking Load And Deflection Of Textile Reinforced Self-stressing Concrete Based On Finite Difference Theory

Concrete is widely used in building structures because of its high compressive strength,good fire resistance and low price.However,most reinforced concrete components work with cracks because of the low tensile strength of concrete.The generation and development of cracks greatly weaken the protective effect of concrete on reinforcement,accelerate the damage development of concrete,promote the corrosion of reinforcement,reduce the cooperative mechanical performance of reinforcement and concrete,and finally threaten the normal use and ultimate bearing capacity of the whole structure.Textile reinforced self-stressing concrete(TRSSC)is made up of the self-stressing concrete and textile,which can produce self-compressive stress of about 1MPa ～ 3Mpa in the matrix before the component is loaded.The weak cracking resistance of concrete matrix is relieved due to the self-compressive stress.The textile can be arranged flexibly,so TRSSC can produce the self-compressive stress of the specified size in the specified position and direction according to the needs,which greatly improve the durability and safety of the structure.However,it is difficult to accurately express the self-stress value due to the restriction of textile by traditional calculation theory and the calculation of cracking load and deflection of TRSSC is still in its infancy,which seriously restrict the application and popularization of TRSSC.Therefore,relying on the National Natural Science Foundation Project(51108207,41430642,42072296),Four aspects are studied in this paper.(1)The basic material performance of self-stressing matrix and ordinary matrix were tested.By analyzing the expansion mechanism of self-stressing concrete matrix,the reasons for the change of mechanical properties of self-stressing concrete matrix are explored;(2)Through the four-point bending test,the influence of concrete matrix type and the number of layers of textile on the cracking load and cracking deflection is studied,and the variation law of cracking load and cracking deflection is analyzed;(3)The expansion of TRSSC beams were measured regularly.Based on the artificial neural network,the variation of the expansion of TRSSC beam with the curing age and the number of layers of textile is studied,which provides a way to quantitatively describe the expansion of TRSSC beam;(4)The self-stress value of TRSSC was calculated according to the expansion of the specimen.Based on elasticity,the cracking load and deflection of TRSSC beam are calculated by finite difference method.The correctness of the calculation results is verified by the test data.This paper explains the reason why TRSSC can improve the cracking resistance of specimens,determines the influencing factors of the cracking load and deflection of TRSSC beams,and establishes a calculation method to describe the cracking load and deflection of TRSSC beams,so as to provide guidance for the application of TRSSC in practical engineering.