锈蚀钢筋混凝土框架节点力学性能退化研究

Study on Mechanical Behavior Degradation of Corroded Reinforced Concrete Frame Joints

目的找出不同钢筋锈蚀率对钢筋混凝土框架节点承载力的退化规律,进而为老旧框架节点的修复与加固提供依据.方法考虑柱端轴压比、约束条件等实际情况,且考虑钢筋强度折减以及钢筋与混凝土之间的摩擦作用,采用位移法对钢筋混凝土框架节点核心区没有配置箍筋的15个模型进行非线性数值分析.结果相同轴压比下,随着钢筋锈蚀率的增大,承载力降低,退化幅度逐渐增大,当锈蚀率达到10%,承载力基本不变,但构件已由延性破坏变为脆性破坏;相同锈蚀率下,增大轴压比,构件的承载力、极限位移呈现出先增大后减小的趋势,轴压比取0.4时,节点表现出较好的力学性能.结论钢筋锈蚀率与轴压比是影响节点力学性能的重要因素.过大钢筋锈蚀率和过大轴压比导致框架节点受单调荷载作用时的极限承载力与极限位移损失严重,节点的强度在锈蚀初期便表现出明显的退化趋势.

This paper is to find out the degeneration law for bearing capacity of reinforced concrete frame under different rebar corrosion rates, and thus provide a basis for the repair and reinforce- ment of the old frame joints. Considering the column end axial compression ratio ,the actual situa- tion of constraint conditions, steel strength reduction and friction between the steel and concrete, using the radial displacement method to simulate rebar corrosion effect on the surrounding con- crete, a nonlinear numerical analysis on 15 models of reinforced concrete frame joints is carded out. Results show that on the same axial compression ratio, with the increase of rebar corrosion rate, carrying capacity decreases, degradation rate gradually increases. When corrosion rate reaches 10% ,the carrying capacity is essentially unchanged ,but component failure is changed from brittleform to ductile form. On the same corrosion rate, with the axial compression ratio increases, the carrying capacity and the ultimate displacement both are increase and then reduce. When the axial compression ratio is O. 4, the joints have better mechanical performances. Conclusion is that rebar corrosion rate and axial compression ratio are important effect factors for joint mechanical behav- ior. Too large rebar corrosion rate and too large axial compression ratio both lead to serious loss of ultimate strength and ultimate displacement of framework joints under monotonic loading. Joint strength in the early rust presents significant degradation.