界面锈蚀钢–混凝土组合梁疲劳后剩余承载力试验研究

Study on the Residual Bearing Capacity of Interfacially Corroded Steel-Concrete Composite Beams after Fatigue Loading

摘要: 为研究界面锈蚀部分抗剪连接钢–混凝土组合梁在疲劳荷载作用下剩余承载性能的退化规律，设计并制作了5根钢–混凝土组合梁试件，在通电加速锈蚀实验基础上，开展静载和疲劳试验。该研究分析了不同锈蚀程度下组合梁的破坏模式、荷载–挠度关系、全截面应变分布及界面滑移特征。结果表明：界面锈蚀显著影响组合梁疲劳后的破坏模式，未锈蚀疲劳试件SFSCB-0最终发生剪切破坏，而锈蚀疲劳试件SFSCB-1~SFSCB-3均主要表现为压弯破坏；各试件荷载–挠度曲线均可分为弹性阶段、弹塑性阶段和破坏阶段，疲劳作用会降低组合梁的承载能力和变形能力；与未锈蚀疲劳试件相比，适度界面锈蚀在一定范围内增强了界面黏结、摩擦和咬合作用，使锈蚀试件的疲劳后剩余承载力有所提高，但随着锈蚀程度进一步增加，该有利作用逐渐减弱；各试件截面应变沿梁高方向总体近似线性分布，整体上基本满足平截面假定，但界面附近应变连续性减弱，表明疲劳作用和界面锈蚀共同削弱了钢梁与混凝土板之间的协同受力能力；荷载–滑移分析表明，未锈蚀疲劳试件更易出现分布型滑移，锈蚀疲劳试件更易表现为局部集中滑移。

Abstract: To investigate the degradation law of the residual bearing capacity of steel-concrete composite beams with partially corroded shear connectors under fatigue loading, five steel-concrete composite beam specimens were designed and fabricated. Based on electrochemical accelerated corrosion tests, static loading tests and fatigue tests were carried out. The failure modes, load-deflection responses, full-section strain distributions, and interfacial slip characteristics of composite beams with different corrosion levels were analyzed. The results show that interfacial corrosion significantly affects the failure mode of composite beams after fatigue loading. The uncorroded fatigue specimen SFSCB-0 eventually failed in shear, whereas the corroded fatigue specimens SFSCB-1 to SFSCB-3 mainly exhibited flexural-compression failure. The load-deflection curves of all specimens can be divided into the elastic stage, elastic-plastic stage, and failure stage, indicating that fatigue loading reduces both the bearing capacity and deformation capacity of the composite beams. Compared with the uncorroded fatigue specimen, moderate interfacial corrosion enhanced the interfacial bonding, friction, and mechanical interlocking to a certain extent, thereby improving the residual bearing capacity after fatigue. However, with further increase in corrosion degree, this beneficial effect gradually weakened. The sectional strain distributions of all specimens were approximately linear along the beam depth, indicating that the plane-section assumption was generally satisfied; however, the continuity of strain near the interface was weakened, demonstrating that fatigue loading and interfacial corrosion jointly reduced the cooperative action between the steel beam and the concrete slab. Load-slip analysis further indicates that the uncorroded fatigue specimen was more likely to exhibit distributed slip, whereas the corroded fatigue specimens were more prone to localized slip concentration.