本研究主要針對鋼筋直徑對疲勞強度之影響討論，並以鋼筋局部高應力集中區提出平均垂直應力比，作為直徑比對疲勞強度之預測模型。目前筆者查詢直徑對疲勞強度影響之相關文獻多為定性描述，因此針對其中定量之文獻進行分析，又因文獻中較少以鋼筋直徑對應力強度因子之影響與疲勞現象作討論及連結，以此為主要動機進行研析。 首先引用相關文獻之回歸經驗式，針對其中參數對疲勞強度之影響及適用範圍進行討論，第二部份利用Abaqus軟體建置鋼筋有限元素模型，並分析改變直徑對其局部高應力集中區之影響情形，第三部份先採BS[1]疲勞強度規範為比較基準，隨後以鋼筋直徑比對應其局部高應力集中區，分別依四種模式建置直徑比對疲勞強度之預測模型並找出最佳者，最後對其進行相應經驗式比較、鋼筋節表面根部曲率半徑與節高比值(r/h)改變之影響等延伸分析討論，以供後續鋼筋疲勞強度研究之參考。 ;The main focus of this study is to investigate the influence of the diameter of reinforcement bars on fatigue strength and propose an average vertical stress ratio for the local high-stress concentration zone of the reinforcement bar as a predictive model for fatigue strength based on diameter ratio. Currently, the literature related to the impact of diameter on fatigue strength mainly consists of qualitative descriptions. Therefore, this research aims to analyze the quantitative literature and explore the link between the diameter of reinforcement bars and stress intensity factors associated with fatigue phenomena, which serves as the primary motivation for this analysis. The first part of the study involves referencing relevant literature and discussing the impact and applicability range of parameters on fatigue strength using regression empirical formulas. In the second part, a finite element model of the reinforcement bar is created using Abaqus software, and the effects of changing the diameter on the local high-stress concentration zone are analyzed. In the third part, the BS [1] fatigue strength standard is adopted as a comparative benchmark, and then predictive models for fatigue strength based on diameter ratio are established in four different modes to find the optimal model. Finally, a comparison of the respective empirical formulas, as well as an extended analysis of the effects of changes in the radius of curvature at the root of the surface of the reinforcement bar section and the ratio of radius to height (r/h), are conducted to provide reference for future research on the fatigue strength of reinforcement bars.
