Reliability Analysis Of Flexural Behavior Of FRC Beams

FRC can enhance flexural capacity, anti-deformation and anti-cracking capabilities of concrete structures. However, with the time of service, due to carbonation of concrete, steel bar corrosion and cracks of FRC beams, its performance must have different levels of attenuation. Many FRC beams in service have potential risk. Some even loss services before their designed life. And it affects the normal use of the structure at last. Therefore, it is important to analysis time-dependent reliability of FRC beams. At present, the study of time-dependent reliability of concrete beams focused on ordinary concrete mostly. Fiber makes the composite effect of its internal components more complicated, which makes its theoretical analysis more difficulty. And the research in this field is still poor.The paper based on structural reliability theory. It seemed the resistance of the structure as a random prosess. Considering the strength of concrete, effective cross-sectional dimensions, coefficients of fiber reinforced and other factors, it inferred the model of reliability analysis of fiber concrete beams’flexural capacity and based on the control of deflection. Followed by an example analysis, with the method of FOSM from both the strength and stiffness to analyze flexural reliability of the structure, and obtain the reliable indicator random variable sensitivity. At last analyze the results.Then, based on the concrete strength, effective cross-sectional dimensions, bond coefficient between steel and concrete, and the uncertainty coefficient’s change with time, the paper establishes a bi-SFRC beams reliability analysis model of flexural capacity, based on the control of deflection and crack width. Then cited an example, discusses the change of random variables with time, use the method of equivalent resistance method and FOSM, at last obtain its time-dependent reliability indicator and time- dependent sensitivity.From the flexural capacity of SFRC beams time-dependent reliability analysis, we can known that the best of steel fiber content conformity with the relevant research; the more the loads the less the reliable indicator and the greater its flexural capacity; in the early stages of service, reliability index first rose and then fell. From the reliability analysis based on control of deflection and crack width, we can known that the larger the steel fiber content, the more the reliable indicator and the greater its anti-deformation and anti-cracking capabilities which meets the results of the test; the less the loads the more the reliable indicator and the greater its resistance to deformation and cracking; consistent with the test results; in the early stages of service, reliability index decline significantly, with longer service time, reliable indicator is moderate, which consistent with experimental data.This paper can be used to calculate the failure probability of the entire structure and study the dynamic reliability. And provide theoretical basis for the improvement of fiber concrete crack resistance and flexural toughness. It also has some reference value for the repair and reinforcement of structural damage. And provide theoretical support for the full use of potential of the material and the development and application of fiber reinforced concrete.