局部锈蚀下Q550E钢梁抗弯性能试验研究

侵蚀环境下高性能钢结构普遍存在局部锈蚀病害，这将削弱结构的整体承载能力。为了研究局部锈蚀对钢结构承载力的影响程度，设计制作了7片H形Q550E高性能钢梁，研究不同局部锈蚀对高性能钢梁抗弯性能的影响。首先对其中6片试验梁的弯剪段和纯弯段开展了不同锈蚀率的加速锈蚀，另1片为未锈蚀对比梁。接着，对试验梁开展四点弯曲分级加载试验，采集并对比分析了试验梁关键截面的应变和挠度数据。结果表明：锈蚀导致试验梁的承载力、屈服挠度、极限挠度和延性降低，相同锈蚀率下纯弯段性能降低程度大于弯剪段；右半截面承载力比下半截面降低程度更大；所有试验梁均为受压翼缘屈曲失稳破坏；SCR梁屈曲发生在弯剪段，其他试验梁屈曲位置位于纯弯段；弹性阶段腹板应变符合平截面假定，试验梁受拉翼缘一般先于受压翼缘屈服，因此随着荷载的增加，会出现截面中性轴上移现象；整体锈蚀比纯弯段下半截面锈蚀时的剩余承载力低，主要因为整体锈蚀时受压翼缘存在锈蚀削弱，导致试验梁屈曲提前，承载力降低；局部锈蚀的不均匀性会产生翼缘应力集中，导致PCR试验梁比整体锈蚀梁承载力低；与普通钢梁相比，锈蚀对于高性能钢梁承载力退化影响更大；对于顶板和底板锈蚀，梁的剩余承载力与其锈蚀程度为线性关系。

Experimental Study of Bending Performance of Q550E Steel Beams Subjected to Local Corrosion

Local corrosion of high-performance steel (HPS) structures is common in corrosive environments, weakens their overall bearing capacity, and compromises their safety. To investigate the effect of local corrosion on the load-carrying capacity of HPS steel structures, seven H-shaped Q550E HPS beams were designed and manufactured to explore the influence of different extents of local corrosion on bending performance. First, the bending-shear sections and pure-bending sections of six of the beams were subjected to electrochemical corrosion at different rates, while the remaining beam was not subjected to corrosion to provide a basis for comparison. Then, four-point bending loading tests were conducted, and the resulting strain and deflection data were collected and compared at the key sections of the test beams. The test results support the following conclusions. ① Corrosion leads to a reduction in the bearing capacity, yield deflection, ultimate deflection, and ductility of HPS beams. The degree of these reductions owing to corrosion in the pure-bending section is greater than that owing to corrosion in the bending-shear section. In the same corroded beam section, the degree of corrosion is greater in the right-half zone than in the lower-half zone. ② All tested beams exhibit buckling failure of the compression flange. The buckling of the SCR beam is located in the corrosion zone of the bending-shear section, whereas the other beams buckle in the pure-bending section. ③ The strain in the corroded web conforms to the plane section assumption and the tension flanges of the beams yield before the compression flanges; thus, the neutral axis of the section increases as the load increases. ④ The residual bearing capacity of the completely corroded beam is smaller than that of the beam with corrosion in the lower-half zone of the pure bending section because the weakening of the compressive flange of the completely corroded beam advances buckling and reduces the bearing capacity. The non-uniformity of local corrosion leads to a stress concentration in the flange, which causes the PCR beam to exhibit a smaller bearing capacity than the completely corroded beam. ⑤ Corrosion has a more significant impact on the bearing capacity degradation of HPS beams than on that of ordinary steel beams. The residual bearing capacity of corroded HPS beams has a linear relationship with the degree of top and bottom flange plates corrosion.