基于加速锈蚀试验的RC梁抗弯性能劣化研究

Deterioration of the Flexural Behavior of RC Beams Based on Accelerated Corrosion Experiments

为了有效预测锈蚀钢筋混凝土梁(RC梁)抗弯性能的劣化规律,基于加速锈蚀试验开展了3组RC梁的抗弯性能研究,探讨了不同纵筋锈蚀率对RC梁破坏形态、跨中截面应变分布和荷载-挠度曲线的影响,在现有理论模型适用性评估的基础上,结合材料时变分析模型,提出了RC梁抗弯承载能力劣化规律的分析方法。研究结果表明:随着纵筋锈蚀程度的增大,RC梁的塑性变形特征不断下降,破坏模式也由塑性纯弯转为脆性剪弯,跨中截面中和轴不断上移,平截面假定逐渐无法满足,而且梁体的抗弯承载能力不断减小,其荷载-挠度曲线的承载平台也逐渐变短直至消失。对现有抗弯承载能力模型的适用性分析发现,孙彬模型的计算精度最高,离散性最小;以该模型为基础所建立的RC梁抗弯承载能力劣化分析方法,可以得到与试验结果较吻合的劣化曲线。

In order to effectively predict the deterioration rule of the flexural behavior of the corroded reinforced concrete beams(RC beams),the flexural behavior study on three groups of RC beams was conducted based on accelerated corrosion method.The influence of different longitudinal reinforcement corrosion rates on the failure mode,strain distribution and load deflection curve of RC beams was discussed.Based on the applicability evaluation of the existing theoretical models,combined with the time-varying material analysis model,an analysis method for the degradation rule of flexural bearing capacity of RC beams was proposed.The results show that with the increase of corrosion degree of longitudinal bars,the plastic deformation characteristics of RC beams continuously decrease,and the failure mode changes from pure plastic bending to brittle shear bending.As the neutral axis of the mid-span section moves upward,the assumption of plane section cannot be satisfied gradually.Moreover,the flexural bearing capacity of the beam decreases continuously,and the bearing platform of load-deflection curve gradually becomes shorter until it disappears.According to the applicability analysis of the existing bending capacity models,it is found that the calculation accuracy of Sun Bin model is the highest and the discreteness is the least.The deterioration analytical method of flexural behavior of RC beams based on the Sun Bin model can obtain the deterioration curves which are in good agreement with the experimental results.