| 姓名 | 陳柏志(Po-Chih Chen) | 電子郵件信箱 | chenpochih@pchome.com.tw | |
| 畢業系所 | 營建工程系碩士班(Department and Graduate Institute of Constrction Engineering) | |||
| 畢業學位 | 碩士(Master) | 畢業時期 | 90學年第2學期 | |
| 論文名稱(中) | 鋼筋拉拔與混凝土握裹破壞之有限元素法分析 | |||
| 論文名稱(英) | Finite Element Analysis of Bond Between Reinforcement and Concrete | |||
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論文使用權限 | 校內外完全公開 | |
| 論文語文/頁數 | 中文/90 | |||
| 摘要(中) | 摘要 混凝土握裹行為特性為相當普遍之研究，然而針對握裹破壞的裂縫發展與超音波波速下降關聯性之研究，則尚處於開發初期的階段。本研究為分析前期研究所得的試驗結果，以3維有限元素套裝軟體ANSYS模擬拉拔試驗，針對鋼筋混凝土之握裹行為、材料強度、裂縫發展與超音波波速之關聯性加以探討。 根據塗佈裂縫法（Smeared Crack Approach）之精神，可假定混凝土與鋼筋接合介面上存在一抗壓強度較為脆弱之碎裂帶，分析結果顯示，拉拔力施加初期裂縫發生於鋼筋竹節的卡楯部分，因此，保護層厚度不足或鋼筋周圍碎裂帶過於脆弱之分析模型，容易受到鋼筋擠壓的影響產生破壞；而具足夠埋入深度之分析模型，其應力將由模型卡楯部分充分傳遞，隨拉拔力上升使裂縫分佈由模型前端向後以環狀方式逐漸向外側擴散，同時，模型前端因裂縫的大量累積，脈波波速隨拉拔力上升有明顯下降趨勢，分析結果大致介於兩組實驗數據之間。模型末端則易受前端試體損壞造成應力轉由後端試體承受的影響，脈波波速有突然下降的情形。 | |||
| 摘要(英) | ABSTRACT The transfer of forces across the interface between concrete and steel by bond development is of fundamental importance to both reinforced concrete design and structural safety. In a previous study, changes in ultrasonic pulse velocity have been observed as the bond stress at the steel-concrete interface exceeded a certain level. As the pull-out load (transferred to induced bond stress) increases, the pulse velocity, measured in perpendicular direction of the steel-concrete interface, also decreases. This phenomenon becomes very significant as the pull-out load approaches the maximum bond strength of the specimen. The goal of current study is to analyze possible connection among steel-concrete bond, crack development, and ultrasonic pulse velocity. It is postulated that the decrease in ultrasonic pulse velocity is related to the formation of micro-crack near the steel-concrete interface. Finite element analysis shows that the initial micro-crack distribution along the path of ultrasonic pulse is critical to the decrease of pulse velocity. The results are probably the first pulse velocity approximation ever made for ultrasonic pulse propagating in a cracked or micro-cracked concrete member. The three-dimensional finite-element model is effective while its computation efficiency is sensitive to mesh size. Low pulse velocity in the first measured point, both seen in the current study and in the published experimental results, is due to the weak bond force provided by a small contact surface. The maximum loads, around 71kN (7200Kg), are also comparable to those of the experimental results. | |||
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