Abstract:Aiming at the problem of brittleness of steel members with crack damage. Most researchers assume that the crack is perpendicular to the stress direction, and assume that the yield ratio will not change with the change of the crack. However, the angle of cracking in actual engineering is random, and the flexural strength ratio of crack-damaged steel members is changed with the crack length. For two different steels, Q235 and Q355, the experimental and analytical research of the damaged steel members with cracks from different angles are carried out in this paper. The brittleness of crack-damaged steel members is investigated by considering different crack angles with varying flexural strength ratios. The research shows that: When the yield strength is calculated, any crack angle can be projected into a crack treatment perpendicular to the force direction. When the relative crack length is certain, the larger the yield strength ratio is, the more likely the cracked steel member presents brittle properties. When the relative crack length increases, the flexural strength ratio of the crack-damaged steel member increases, and the residual ultimate strength formula is improved by using a variable flexural strength ratio, so that the error between the formula calculated value and the test value is less than 1%. The research results of this paper have certain theoretical value and practical significance for the prevention, repair and strengthening of cracked steel members in the later stage.