非均匀锈蚀钢筋拉伸性能试验与模拟

Tensile Properties Test and Simulation of Non-uniform Corroded Reinforcement

钢筋的非均匀锈蚀形貌是决定锈蚀钢筋力学性能的关键.结合“电渗-恒电流-干湿循环”加速锈蚀方法与3D扫描技术,获取了13根不同锈蚀程度、不同直径钢筋试件的锈蚀形貌,并通过单调拉伸试验和数值模拟,研究了锈蚀程度及钢筋直径对其力学性能的影响.结果表明:钢筋的名义屈服强度、名义极限强度、名义弹性模量、硬化起始应变和名义峰值应变等特征参数均随着锈蚀程度的增加而降低,且较小直径钢筋的强度特征值受锈蚀影响更为显著;微段切分法的分析结果表明,锈蚀钢筋名义力学性能的劣化是由截面积削弱引发的,其实际力学性能并未改变;根据已有试验数据和模拟结果,以最大截面锈蚀率和平均质量锈蚀率作为锈蚀程度量化指标对各力学性能特征参数退化规律进行了标定,进而建立了非均匀锈蚀钢筋拉伸本构模型.

The non-uniform corrosion morphology of steel bars is the key to determine the mechanical properties of corroded steel bars. The accelerated corrosion method of‘electroosmotic-constant current-dry-wet cycle’and 3D scanning technology were combined to obtain the corrosion morphology of 13 steel specimens with different corrosion degrees and diameters. The effects of corrosion degree and steel diameter on the mechanical properties were studied through monotonic tensile test and numerical simulation. The results show that the nominal yield strength,nominal ultimate strength,nominal elastic modulus,hardening initial strain and nominal peak strain of steel bars decrease with the increase of corrosion degree,and the strength characteristic value of small diameter steel bars is more significantly affected by corrosion. However,the analysis results of micro-section method show that the deterioration of nominal mechanical properties of corroded steel bars is caused by the weakening of cross-sectional area,and the actual mechanical properties do not change. According to the test data and simulation results,the degradation law of each mechanical property parameter is calibrated with the maximum cross-section corrosion rate and the average mass corrosion rate as the quantitative indexes of corrosion degree,then the tensile constitutive model of non-uniform corroded reinforcement is established.