| 摘要: |
| 为模拟局部锈蚀对钢筋静力及疲劳性能的影响，对4种缺口形状、6种缺口尺寸的100根钢筋进行轴向静力拉伸和疲劳拉伸试验.基于静力拉伸试验结果，给出了缺口形状、缺口深度与钢筋屈服载荷、极限荷载间的定量关系，分析了缺口尺寸对应力集中系数的影响；基于疲劳拉伸试验结果，研究了缺口形状和缺口尺寸对钢筋疲劳寿命的影响，建立了钢筋应力范围疲劳寿命缺口深度的曲线方程；在试验基础上，建立了精细有限元三维实体计算模型，分析了缺口附近的应力分布状态，解释了坑蚀形态导致钢筋性能退化的原因.结果表明：三角形缺口应力集中系数最大，依次为变长度三角形、径向椭圆形和轴向椭圆形，应力集中程度随应力水平和缺口深度的增加而增大；不同缺口类型钢筋的实际应力范围和疲劳寿命在对数坐标下呈线性关系；三角形和变长度三角形锈坑应力集中梯度较大，率先进入塑性变形阶段，从而较早发生破坏. |
| 关键词: 锈蚀模拟 应力集中 疲劳 有限元方法 |
| DOI：103969/j.issn.1007 9629201902013 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目(51508036,51478050);国家重点基础研究发展计划(973计划)项目(2015CB057705);长沙市杰出创新青年培养计划项目(kq1802012);湖南省教育厅科学研究项目(17B012) |
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| Experimental and Numerical Analysis on Mechanical Behavior of Different Notched Steel Bars |
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MA Yafei, WANG Qiang, WANG Lei, ZHANG Jianren
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School of Civil Engineering, Changsha University of Science & Technology, Changsha 410114, China
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| Abstract: |
| To simulate the effects of pitting corrosion morphologies on the mechanical behavior of steel bars, tensile static and fatigue tests were conducted on one hundred steel bars. Specimens of four notch shapes, six notch sizes were chosen for test. Quantitative relationships of the yield and the ultimate load under different notch depths were obtained based on the tensile test. The stress concentration coefficients under various notches were also compared. The effect of notch shape and notch size on the fatigue life of steel bars was observed based on the fatigue tensile test. The equations for stress range fatigue life notch depth were also established. Following that, the stress distribution near the notches was analyzed, and corrosion pit induced performance degradation of steel bars was explained by establishing an accurate three dimensional finite element model. The results show that triangular notch has the maximum stress concentration coefficient under a same notch depth, followed by length variable triangle, radial ellipse and axial ellipse shaped notch. The magnitude of stress concentration at the notch location increased with increasing stress level and notch depth. A linear relationship is observed for the stress range and fatigue life of the notched steel bars in logarithmic scale. The triangle and length variable triangle corrosion pits have a relatively higher stress concentration gradient and will lead the steel to enter a plastic deformation stage firstly until failure. |
| Key words: corrosion simulation stress concentration fatigue finite element method |
