台灣高強度混凝土彈性模數預估公式研究

Study of Prediction Equation for Modulus of Elasticity of High Strength Concrete in Taiwan

廖文正(Wen-Cheng Liao) ； 胡瑋秀(Wei-Xiu Hu)

《結構工程》 32卷3期 (2017/09) Pp. 5-26

https://doi.org/10.6849/SE.201709_32(3).0001

摘要

彈性模數為混凝土在工程設計中的重要材料性質，影響混凝土變形，也是計算撓度和剛度的重要參數。台灣現積極研發New RC 建築技術，採高強度混凝土（f’_c ＞ 700 kgf/cm^2）搭配高強度鋼筋，朝向超高層鋼筋混凝土建築發展；惟台灣目前對於高強度混凝土彈性模數預估式一般仍採用美國混凝土學會ACI318 或ACI 363 相關規定，然而相關研究已發現由於高漿體量、低粒料強度與矽灰添加等特性，台灣高強度混凝土的彈性模數預估值明顯高估。為了能獲得較準確的彈性模數，須提出一個符合台灣高強度混凝土材料特性之評估計算公式。本研究收集國內本土471 筆的試驗資料，對各參數進行迴歸分析，將矽灰添加等重要參數納入考量；根據研究成果，本研究以ACI 363 彈性模數預估公式為基礎，乘上矽灰折減係數 k_(sf)，除了易於業界計算外，並可反映台灣混凝土彈性模數偏低的現象，並做為未來New RC 構件設計及工程規範修訂的參考。

關鍵字

高強度混凝土 ； 彈性模數 ； 抗壓強度 ； 矽灰 ； New RC

並列摘要

The modulus of elasticity of concrete is an important factor in design of RC structures. Modulus of elasticity is also essential for engineers to estimate deflections and stiffness of RC members. Nowadays, Taiwan New RC project is developing to reduce the member sections and increase the available space of high rise buildings by using high strength concrete (f'c ＞ 700 kgf/cm^2) and high strength rebars. However, the prediction and calculation of modulus of elasticity of high strength concrete in Taiwan is still mainly referred to ACI318 or ACI363. It was confirmed that modulus of elasticity of high strength concrete is usually overestimated due to less coarse aggregate amount and high paste volume. In order to gain precise modulus of elasticity, it is necessary to find out an equation which can reflect materials characteristic in Taiwan. This study collects 471 data sets of high strength concrete in Taiwan. By regression analysis with certain key parameters, such as silica fume, a new and practical prediction equation based on the ACI318 is proposed. This equation is easy to calculate and reflects the low modulus of elasticity characteristics in Taiwan. It can offer more accurate estimation of modulus of elasticity for New RC member design.

並列關鍵字

High Strength Concrete ； Modulus of Elasticity ； Compressive Strength ； Silica Fume ； New RC